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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT
INVESTMENT COMPANIES

Investment Company Act file number			811- 4430

	Dreyfus 100% U.S. Treasury Money Market Fund
	(Exact name of Registrant as specified in charter)

	c/o The Dreyfus Corporation 200 Park Avenue New York, New York 10166
	(Address of principal executive offices) (Zip code)

	Michael A. Rosenberg, Esq. 200 Park Avenue New York, New York 10166
	(Name and address of agent for service)

Registrant's telephone number, including area code:				(212) 922-6000

Date of fiscal year end:		12/31
Date of reporting period:		12/31/10

-1-

	Contents
	THE FUND
2	A Letter from the Chairman and CEO
3	Discussion of Fund Performance
6	Understanding Your Fund’s Expenses
6	Comparing Your Fund’s Expenses With Those of Other Funds
7	Statement of Investments
8	Statement of Assets and Liabilities
9	Statement of Operations
10	Statement of Changes in Net Assets
11	Financial Highlights
12	Notes to Financial Statements
18	Report of Independent Registered Public Accounting Firm
19	Important Tax Information
20	Information About the Review and Approval of the Fund’s Management Agreement
24	Board Members Information
26	Officers of the Fund
	FOR MORE INFORMATION
	Back Cover

Dreyfus 100% U.S. Treasury
Money Market Fund

The Fund

A LETTER FROM THE CHAIRMAN AND CEO

Dear Shareholder:

We are pleased to present this annual report for Dreyfus 100% U.S. Treasury Money Market Fund, covering the 12-month period from January 1, 2010, through December 31, 2010.

Although 2010 proved to be a volatile year for many longer-term assets, such as stocks and bonds, the reporting period ended with many asset categories producing respectable, positive returns. Investors’ early concerns regarding sovereign debt issues in Europe and stubbornly high unemployment in the United States later gave way to optimism that massive economic stimulus programs, robust growth in the world’s emerging markets, a strong holiday retail season and rising corporate earnings signaled better economic times ahead.

Although U.S. GDP growth was positive throughout the reporting period, the economic recovery has been milder than historical averages. Therefore, we are guardedly optimistic regarding the U.S. economy’s prospects in 2011, and many experts believe inflationary pressures and short-term interest rates should remain low over the near term, potentially preventing any significant rise in money market yields.What does this mean for your investment portfolio?We suggest talking to your financial advisor, who can help you review your allocations and your current liquid asset needs, and identify potential opportunities suitable for your individual needs and risk tolerance in today’s market environment.

For information about how the fund performed during the reporting period, as well as general market perspectives, we provide a Discussion of Fund Performance on the pages that follow.

Thank you for your continued confidence and support.

Jonathan R. Baum
Chairman and Chief Executive Officer
The Dreyfus Corporation
January 18, 2011

DISCUSSION OF FUND PERFORMANCE

For the period of January 1, 2010, through December 31, 2010, as provided by Bernard W. Kiernan, Jr., Senior Portfolio Manager

Fund and Market Performance Overview

For the 12-month period ended December 31, 2010, Dreyfus 100% U.S.Treasury Money Market Fund produced a yield of 0.00%.Taking into account the effects of compounding, the fund provided an effective yield of 0.00% for the same period.¹

Yields on U.S. Treasury bills remained near historical lows throughout 2010 as the Federal Reserve Board (the “Fed”) left its target for short-term interest rates unchanged in a generally sluggish economic environment.

The Fund’s Investment Approach

The fund seeks as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity.The fund also seeks to maintain a stable share price of $1.00.To pursue this goal, the fund invests only in U.S. Treasury securities. As a money market fund, it is subject to strict federal requirements and effective June 30, 2010, must maintain a dollar-weighted average portfolio maturity of 60 days or less and its dollar-weighted average life to 120 days.

Recovery Strengthened but Fed Remained on Hold

The year 2010 began in the midst of an economic recovery fueled, in part, by an overnight federal funds rate that has remained unchanged since December 2008 in a range between 0% and 0.25%. While the economy expanded in the first quarter of 2010 at a relatively mild 3.7% annualized rate, it was encouraging news nonetheless for investors eager to see an end to recession. In fact, job creation began to improve during the first quarter after many months of losses.


The Fund	3

DISCUSSION OF FUND PERFORMANCE (continued)

Investors were further cheered in May, when 431,000 additional new jobs were created, although many were temporary government workers hired for the 2010 Census. However, the economic outlook soon took a turn for the worse when a resurgent sovereign debt crisis in Europe rattled investors. U.S. industrial production moderated in June, and private-sector job growth proved more anemic than many analysts expected. U.S. GDP declined to an annualized 1.7% rate during the second quarter.

In July, the manufacturing and service sectors of the U.S. economy continued to expand. Still, total nonfarm payroll employment fell by 131,000 jobs in July, reflecting the end of temporary census hiring. Sales of new homes fell to a 47-year low in August, while purchases of existing homes plummeted to a 15-year low.The unemployment rate rose to 9.6%, as only 67,000 jobs were created in the private sector during August. Economic data released in September appeared to confirm that the economic recovery, while intact, remained tenuous as employment and housing data showed few signs of improvement. U.S. GDP grew at a 2.6% annualized rate in the third quarter of 2010.

In response to the sluggish rebound, the Fed indicated in September that it would embark on a second round of quantitative easing of monetary policy by purchasing $600 million of U.S.Treasury securities.This move was designed to fight deflationary forces and encourage lending by injecting more cash into the financial system. Indeed, October brought better economic news. The private sector added 159,000 jobs, with much of the gain coming from the services sector. However, issues regarding the banking industry’s foreclosure process further clouded an already murky outlook for home values.

Economic data remained encouraging in November, except for one critical measure: the economy created only 93,000 jobs during the month. Yet, the manufacturing and service sectors continued to improve, and even the housing market posted better sales data.

December continued to show signs of improvement, including better data from the labor market as new unemployment claims moderated and the unemployment rate eased to 9.4%. The manufacturing sector expanded for the 17th consecutive month, and the holiday season proved to be a relatively healthy one for retailers, bolstering the services sector.

Quality and Liquidity Are Paramount

The low federal funds rate kept money market yields near zero percent, and with narrow yield differences along the market’s maturity spectrum. It continued to make little sense to incur the additional interest-rate risks that longer-dated U.S.Treasury bills typically entail.Therefore, we maintained the fund’s weighted average maturity in a range that was roughly in line with industry averages.

The economic recovery appears to be gathering momentum, and we are hopeful that U.S. Treasury yields will respond to a more constructive market environment in 2011. In the meantime, as we have for some time, we intend to maintain the fund’s focus on liquidity.

January 18, 2011


	An investment in the fund is not insured or guaranteed by the FDIC or any other government
	agency.Although the fund seeks to preserve the value of your investment at $1.00 per share, it is
	possible to lose money by investing in the fund.
1	Effective yield is based upon dividends declared daily and reinvested monthly. Past performance is
	no guarantee of future results.Yields fluctuate.Yields provided for the fund reflect the absorption of
	certain fund expenses by The Dreyfus Corporation pursuant to an undertaking in effect that may
	be extended, terminated or modified at any time. Had these expenses not been absorbed, fund
	yields would have been lower, and in some cases, 7-day yields during the reporting period would
	have been negative absent the expense absorption.


The Fund	5

UNDERSTANDING YOUR FUND’S EXPENSES (Unaudited)

As a mutual fund investor, you pay ongoing expenses, such as management fees and other expenses. Using the information below, you can estimate how these expenses affect your investment and compare them with the expenses of other funds.You also may pay one-time transaction expenses, including sales charges (loads) and redemption fees, which are not shown in this section and would have resulted in higher total expenses. For more information, see your fund’s prospectus or talk to your financial adviser.

Review your fund’s expenses

The table below shows the expenses you would have paid on a $1,000 investment in Dreyfus 100% U.S.Treasury Money Market Fund from July 1, 2010 to December 31, 2010. It also shows how much a $1,000 investment would be worth at the close of the period, assuming actual returns and expenses.

Expenses and Value of a $1,000 Investment
assuming actual returns for the six months ended December 31, 2010


Expenses paid per $1,000^†	$ .71
Ending value (after expenses)	$1,000.00

COMPARING YOUR FUND’S EXPENSES
WITH THOSE OF OTHER FUNDS (Unaudited)

Using the SEC’s method to compare expenses

The Securities and Exchange Commission (SEC) has established guidelines to help investors assess fund expenses. Per these guidelines, the table below shows your fund’s expenses based on a $1,000 investment, assuming a hypothetical 5% annualized return. You can use this information to compare the ongoing expenses (but not transaction expenses or total cost) of investing in the fund with those of other funds.All mutual fund shareholder reports will provide this information to help you make this comparison. Please note that you cannot use this information to estimate your actual ending account balance and expenses paid during the period.

Expenses and Value of a $1,000 Investment
assuming a hypothetical 5% annualized return for the six months ended December 31, 2010


Expenses paid per $1,000^†	$ .71
Ending value (after expenses)	$1,024.50

† Expenses are equal to the fund’s annualized expense ratio of .14%, multiplied by the average account value over the

period, multiplied by 184/365 (to reflect the one-half year period).

STATEMENT OF INVESTMENTS

December 31, 2010


	Annualized
	Yield on
	Date of	Principal
U.S. Treasury Bills—87.4%	Purchase (%)	Amount ($)	Value ($)
1/6/11	0.12	30,409,000	30,408,490
1/13/11	0.19	55,000,000	54,996,608
1/20/11	0.07	38,000,000	37,998,517
1/27/11	0.14	99,000,000	98,989,647
2/3/11	0.09	224,000,000	223,981,502
2/10/11	0.13	80,000,000	79,989,028
2/17/11	0.14	50,000,000	49,991,187
2/24/11	0.11	100,000,000	99,983,500
3/3/11	0.15	7,000,000	6,998,280
3/17/11	0.13	228,000,000	227,938,250
Total U.S. Treasury Bills
(cost $911,275,009)			911,275,009

U.S. Treasury Notes—12.3%
5/2/11	0.21	51,000,000	51,789,121
5/2/11	0.25	25,000,000	25,051,985
6/30/11	0.22	50,000,000	51,217,623
Total U.S. Treasury Notes
(cost $128,058,729)			128,058,729
Total Investments (cost $1,039,333,738)		99.7%	1,039,333,738
Cash and Receivables (Net)		.3%	3,632,041
Net Assets		100.0%	1,042,965,779


Portfolio Summary (Unaudited)^†
	Value (%)		Value (%)
U.S. Treasury Bills	87.4	U.S. Treasury Notes	12.3
			99.7
† Based on net assets.
See notes to financial statements.


The Fund	7

STATEMENT OF ASSETS AND LIABILITIES

December 31, 2010


	Cost	Value
Assets ($):
Investments in securities—See Statement of Investments	1,039,333,738	1,039,333,738
Cash		5,902,938
Interest receivable		460,389
Prepaid expenses		92,473
		1,045,789,538
Liabilities ($):
Due to The Dreyfus Corporation and affiliates—Note 2(b)		110,650
Payable for shares of Beneficial Interest redeemed		2,596,245
Accrued expenses		116,864
		2,823,759
Net Assets ($)		1,042,965,779
Composition of Net Assets ($):
Paid-in capital		1,042,967,032
Accumulated net realized gain (loss) on investments		(1,253)
Net Assets ($)		1,042,965,779
Shares Outstanding
(unlimited number of $.001 par value shares of Beneficial Interest authorized)		1,042,681,147
Net Asset Value, offering and redemption price per share ($)		1.00

See notes to financial statements.

STATEMENT OF OPERATIONS

Year Ended December 31, 2010


Investment Income ($):
Interest Income	1,562,835
Expenses:
Management fee—Note 2(a)	5,456,434
Shareholder servicing costs—Note 2(b)	688,940
Trustees’ fees and expenses—Note 2(c)	101,901
Custodian fees—Note 2(b)	87,284
Professional fees	74,641
Prospectus and shareholders’ reports	66,063
Registration fees	36,525
Miscellaneous	31,767
Total Expenses	6,543,555
Less—reduction in expenses due to undertaking—Note 2(a)	(4,979,775)
Less—reduction in fees due to earnings credits—Note 2(b)	(1,386)
Net Expenses	1,562,394
Investment Income—Net	441
Net Realized Gain (Loss) on Investments—Note 1(b) ($)	(1,253)
Net (Decrease) in Net Assets Resulting from Operations	(812)

See notes to financial statements.


The Fund	9

STATEMENT OF CHANGES IN NET ASSETS


	Year Ended December 31,
	2010	2009
Operations ($):
Investment income—net	441	324,825
Net realized gain (loss) on investments	(1,253)	60,256
Net Increase (Decrease) in Net Assets
Resulting from Operations	(812)	385,081
Dividends to Shareholders from ($):
Investment income—net	(20,751)	(425,830)
Beneficial Interest Transactions ($1.00 per share):
Net proceeds from shares sold	778,960,367	1,800,692,161
Dividends reinvested	19,980	391,055
Cost of shares redeemed	(966,384,872)	(2,834,890,355)
Increase (Decrease) in Net Assets from
Beneficial Interest Transactions	(187,404,525)	(1,033,807,139)
Total Increase (Decrease) in Net Assets	(187,426,088)	(1,033,847,888)
Net Assets ($):
Beginning of Period	1,230,391,867	2,264,239,755
End of Period	1,042,965,779	1,230,391,867

See notes to financial statements.

FINANCIAL HIGHLIGHTS

The following table describes the performance for the fiscal periods indicated. Total return shows how much your investment in the fund would have increased (or decreased) during each period, assuming you had reinvested all dividends and distributions.These figures have been derived from the fund’s financial statements.


		Year Ended December 31,
	2010	2009	2008	2007	2006
Per Share Data ($):
Net asset value,
beginning of period	1.00	1.00	1.00	1.00	1.00
Investment Operations:
Investment income—net	.000^a	.000^a	.014	.041	.040
Distributions:
Dividends from investment income—net	(.000)^a	(.000)^a	(.014)	(.041)	(.040)
Net asset value, end of period	1.00	1.00	1.00	1.00	1.00
Total Return (%)	.00^b	.02	1.37	4.16	4.07
Ratios/Supplemental Data (%):
Ratio of total expenses
to average net assets	.60	.60	.59	.65	.70
Ratio of net expenses
to average net assets	.14	.36	.58	.65	.70
Ratio of net investment income
to average net assets	.00^b	.02	1.00	4.05	4.00
Net Assets, end of period
($ x 1,000)	1,042,966	1,230,392	2,264,240	604,271	563,128


a	Amount represents less than $.001 per share.
b	Amount represents less than .01%.

See notes to financial statements.


The Fund	11

NOTES TO FINANCIAL STATEMENTS

NOTE 1—Significant Accounting Policies:

Dreyfus 100% U.S.Treasury Money Market Fund (the “fund”) is registered under the Investment Company Act of 1940, as amended (the “Act”), as a diversified open-end management investment company. The fund’s investment objective is to seek as high a level of current income as is consistent with the preservation of capital and the maintenance of liquidity. The Dreyfus Corporation (the “Manager” or “Dreyfus”), a wholly-owned subsidiary of The Bank of New York Mellon Corporation (“BNY Mellon”), serves as the fund’s investment advisor. MBSC Securities Corporation (the “Distributor”), a wholly-owned subsidiary of the Manager, is the distributor of the fund’s shares, which are sold to the public without a sales charge.

It is the fund’s policy to maintain a continuous net asset value per share of $1.00; the fund has adopted certain investment, portfolio valuation and dividend and distribution policies to enable it to do so.There is no assurance, however, that the fund will be able to maintain a stable net asset value per share of $1.00.

The Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) is the exclusive reference of authoritative U.S. generally accepted accounting principles (“GAAP”) recognized by the FASB to be applied by nongovernmental entities. Rules and interpretive releases of the Securities and Exchange Commission (“SEC”) under authority of federal laws are also sources of authoritative GAAP for SEC registrants. The fund’s financial statements are prepared in accordance with GAAP, which may require the use of management estimates and assumptions.Actual results could differ from those estimates.

The fund enters into contracts that contain a variety of indemnifications. The fund’s maximum exposure under these arrangements is unknown.The fund does not anticipate recognizing any loss related to these arrangements.

(a) Portfolio valuation: Investments in securities are valued at amortized cost in accordance with Rule 2a-7 of the Act, which has been determined by the Board of Trustees to represent the fair value of the fund’s investments.

The fair value of a financial instrument is the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (i.e. the exit price). GAAP establishes a fair value hierarchy that prioritizes the inputs of valuation techniques used to measure fair value.This hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements).

Additionally, GAAP provides guidance on determining whether the volume and activity in a market has decreased significantly and whether such a decrease in activity results in transactions that are not orderly. GAAP requires enhanced disclosures around valuation inputs and techniques used during annual and interim periods.

Various inputs are used in determining the value of the fund’s investments relating to fair value measurements.These inputs are summarized in the three broad levels listed below:

Level 1—unadjusted quoted prices in active markets for identical investments.

Level 2—other significant observable inputs (including quoted prices for similar investments, interest rates, prepayment speeds, credit risk, etc.).

Level 3—significant unobservable inputs (including the fund’s own assumptions in determining the fair value of investments).

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those


The Fund	13

NOTES TO FINANCIAL STATEMENTS (continued)

securities. For example, money market securities are valued using amortized cost, in accordance with rules under the Act. Generally, amortized cost approximates the current fair value of a security, but since the value is not obtained from a quoted price in an active market, such securities are reflected as Level 2.

The following is a summary of the inputs used as of December 31, 2010 in valuing the fund’s investments:


	Short-Term
Valuation Inputs	Investments ($)^†
Level 1—Unadjusted Quoted Prices	—
Level 2—Other Significant Observable Inputs	1,039,333,738
Level 3—Significant Unobservable Inputs	—
Total	1,039,333,738


†	See Statement of Investments for additional detailed categorizations.

(b) Securities transactions and investment income: Securities transactions are recorded on a trade date basis. Interest income, adjusted for accretion of discount and amortization of premium on investments, is earned from settlement date and recognized on the accrual basis. Realized gains and losses from securities transactions are recorded on the identified cost basis. Cost of investments represents amortized cost.

(c) Dividends to shareholders: It is the policy of the fund to declare dividends daily from investment income-net. Such dividends are paid monthly. Dividends from net realized capital gains, if any, are normally declared and paid annually, but the fund may make distributions on a more frequent basis to comply with the distribution requirements of the Internal Revenue Code of 1986, as amended (the “Code”).To the extent that net realized capital gains can be offset by capital loss carryovers, it is the policy of the fund not to distribute such gains.

(d) Federal income taxes: It is the policy of the fund to continue to qualify as a regulated investment company, if such qualification is in the best interests of its shareholders, by complying with the applicable pro-

visions of the Code, and to make distributions of taxable income sufficient to relieve it from substantially all federal income and excise taxes.

As of and during the period ended December 31, 2010, the fund did not have any liabilities for any uncertain tax positions.The fund recognizes interest and penalties, if any, related to uncertain tax positions as income tax expense in the Statement of Operations. During the period, the fund did not incur any interest or penalties.

Each of the tax years in the four-year period ended December 31, 2010 remains subject to examination by the Internal Revenue Service and state taxing authorities.

At December 31, 2010, the components of accumulated earnings on a tax basis were substantially the same as for financial reporting purposes.

The accumulated capital loss carryover of $1,253 is available for federal income tax purposes to be applied against future net securities profits, if any, realized subsequent to December 31, 2010. If not applied, the carryover expires in fiscal 2018.

The tax character of distributions paid to shareholders during the fiscal periods ended December 31, 2010 and December 31, 2009 were all ordinary income.

During the period ended December 31, 2010, as a result of permanent book to tax differences primarily due to dividend reclassification, the fund increased accumulated undistributed investment income-net by $20,310, decreased accumulated net realized gain (loss) on investments by $17,641 and decreased paid-in capital by $2,669. Net assets and net asset value per share were not affected by this reclassification.

At December 31, 2010, the cost of investments for federal income tax purposes was substantially the same as the cost for financial reporting purposes (See the Statement of Investments).


The Fund	15

NOTES TO FINANCIAL STATEMENTS (continued)

NOTE 2—Management Fee and Other Transactions With Affiliates:

(a) Pursuant to a management agreement with the Manager, the management fee is computed at the annual rate of .50% of the value of the fund’s average daily net assets and is payable monthly.

The Manager has undertaken to reimburse expenses in the event that current yields drop below a certain level. Such expense limitations may fluctuate daily, are voluntary and not contractual and may be terminated at any time. The reduction in expenses, pursuant to the undertakings amounted to $4,979,775, during the period ended December 31, 2010.

(b) Under the Shareholder Services Plan, the fund reimburses the Distributor an amount not to exceed an annual rate of .25% of the value of the fund’s average daily net assets for certain allocated expenses of providing personal services and/or maintaining shareholder accounts.The services provided may include personal services relating to shareholder accounts, such as answering shareholder inquiries regarding the fund and providing reports and other information, and services related to the maintenance of shareholder accounts. During the period ended December 31, 2010, the fund was charged $487,116 pursuant to the Shareholder Services Plan.

The fund compensates Dreyfus Transfer, Inc., a wholly-owned subsidiary of the Manager, under a transfer agency agreement for providing personnel and facilities to perform transfer agency services for the fund. During the period ended December 31, 2010, the fund was charged $91,042 pursuant to the transfer agency agreement, which is included in Shareholder servicing costs in the Statement of Operations.

The fund has arrangements with the custodian and cash management bank whereby the fund may receive earnings credits when positive cash balances are maintained, which are used to offset custody and cash management fees. For financial reporting purposes, the fund includes net earnings credits as an expense offset in the Statement of Operations.

The fund compensates The Bank of New York Mellon, a subsidiary of BNY Mellon and an affiliate of Dreyfus, under a cash management agreement for performing cash management services related to fund subscriptions and redemptions. During the period ended December 31, 2010, the fund was charged $19,546 pursuant to the cash management agreement, which is included in Shareholder servicing costs in the Statement of Operations. These fees were partially offset by earnings credits of $1,185.

The fund also compensates The Bank of New York Mellon under a custody agreement for providing custodial services for the fund. During the period ended December 31, 2010, the fund was charged $87,284 pursuant to the custody agreement.These fees were partially offset by earnings credits of $201.

During the period ended December 31, 2010, the fund was charged $6,243 for services performed by the Chief Compliance Officer.

The components of “Due to The Dreyfus Corporation and affiliates” in the Statement of Assets and Liabilities consist of: management fees $451,447, shareholder services plan fees $37,000, custodian fees $27,877, chief compliance officer fees $1,728 and transfer agency per account fees $7,755, which are offset against an expense reimbursement currently in effect in the amount of $415,157.

(c) Each Board member also serves as a Board member of other funds within the Dreyfus complex. Annual retainer fees and attendance fees are allocated to each fund based on net assets.


The Fund	17

REPORT OF INDEPENDENT REGISTERED

PUBLIC ACCOUNTING FIRM

Shareholders and Board of Trustees

Dreyfus 100% U.S. Treasury Money Market Fund

We have audited the accompanying statement of assets and liabilities of Dreyfus 100% U.S.Treasury Money Market Fund, including the statement of investments, as of December 31, 2010, and the related statement of operations for the year then ended, the statement of changes in net assets for each of the two years in the period then ended, and financial highlights for each of the years indicated therein. These financial statements and financial highlights are the responsibility of the Fund’s management. Our responsibility is to express an opinion on these financial statements and financial highlights based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States).Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements and financial highlights are free of material misstatement.We were not engaged to perform an audit of the Fund’s internal control over financial reporting. Our audits included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Fund’s internal control over financial reporting.Accordingly, we express no such opinion.An audit also includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements and financial highlights, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. Our procedures included confirmation of securities owned as of December 31, 2010 by correspondence with the custodian. We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the financial statements and financial highlights referred to above present fairly, in all material respects, the financial position of Dreyfus 100% U.S. Treasury Money Market Fund at December 31, 2010, the results of its operations for the year then ended, the changes in its net assets for each of the two years in the period then ended, and the financial highlights for each of the indicated years, in conformity with U.S. generally accepted accounting principles.

New York, New York
February 28, 2011

INFORMATION ABOUT THE REVIEW AND APPROVAL

OF THE FUND’S MANAGEMENT AGREEMENT (Unaudited)

At a meeting of the fund’s Board held on July 13, 2010, the Board considered the re-approval of the fund’s Management Agreement with Dreyfus for a one-year term ending July 31, 2011. The Board members, none of whom are “interested persons” (as defined in the Investment Company Act of 1940, as amended) of the fund, were assisted in their review by independent legal counsel and met with counsel in executive session separate from representatives of Dreyfus. In considering the re-approval of the Management Agreement, the Board considered all factors that it believed to be relevant, including, among other things, the factors discussed below.

Analysis of Nature, Extent and Quality of Services Provided to the Fund. The Board members received a presentation from representatives of Dreyfus regarding services provided to the fund and other funds in the Dreyfus fund complex, and discussed the nature, extent and quality of the services provided to the fund pursuant to its Management Agreement. Dreyfus’ representatives reviewed the fund’s distribution of accounts and the relationships Dreyfus has with various intermediaries and the different needs of each. Dreyfus’ representatives noted the various distribution channels for the fund as well as the diverse methods of distribution among other funds in the Dreyfus fund complex, and Dreyfus’ corresponding need for broad, deep, and diverse resources to be able to provide ongoing shareholder services to each distribution channel, including those of the fund. Dreyfus also provided the number of accounts investing in the fund, as well as the fund’s asset size.

The Board members also considered Dreyfus’ research and portfolio management capabilities and Dreyfus’ oversight of day-to-day fund operations, including fund accounting, administration and assistance in meeting legal and regulatory requirements. The Board members also considered Dreyfus’ extensive administrative, accounting and compliance infrastructure.

Comparative Analysis of the Fund’s Performance and Management Fee and Expense Ratio. The Board members reviewed the fund’s performance for various periods and compared the fund’s performance to the performance of a group of comparable retail no-load U.S.Treasury

money market funds (the “Performance Group”) and to a larger universe of funds consisting of all retail U.S.Treasury money market funds (the “Performance Universe”), selected and provided by Lipper, Inc., an independent provider of investment company data.The Board was provided with a description of the methodology Lipper used to select the Performance Group and Performance Universe, as well as the Expense Group and Expense Universe (discussed below). The Board members discussed the results of the comparisons and noted that the fund’s total return performance was above or at the Performance Group and Performance Universe medians for all periods, except the one-year period ended May 31, 2010, when it was slightly below the Performance Group and Performance Universe medians.

The Board members also discussed the fund’s management fee and expense ratio and reviewed the range of actual and contractual management fees and total expense ratios compared to a group of comparable funds (the “Expense Group”) and a broader group of funds (the “Expense Universe”), each selected and provided by Lipper.The Board noted that Dreyfus has undertaken to limit fund expenses to maintain the minimum yield floor limit of 0.00%. The Board noted that such expense limitations are voluntary, not contractual, and may be terminated by Dreyfus at any time without notice. The Board members noted that the fund’s actual management fee was lower than the Expense Group median and higher than the Expense Universe median, the contractual management fee was higher than the Expense Group median and the fund’s total expense ratio was lower than the Expense Group and Expense Universe medians.

Representatives of Dreyfus reviewed with the Board members the fees paid to Dreyfus or its affiliates by mutual funds managed by Dreyfus or its affiliates with similar investment objectives, policies and strategies as the fund (the “Similar Funds”). It was noted that there were no other accounts managed by Dreyfus or its affiliates with similar investment objectives, policies and strategies as the fund. The Board members


The Fund	21

INFORMATION ABOUT THE REVIEW AND APPROVAL OF THE

FUND’S MANAGEMENT AGREEMENT (Unaudited) (continued)

considered the relevance of the fee information provided for the Similar Funds to evaluate the appropriateness and reasonableness of the fund’s management fee.

Analysis of Profitability and Economies of Scale. Dreyfus’ representatives reviewed the dollar amount of expenses allocated and profit received by Dreyfus and the method used to determine such expenses and profit. The Board previously had been provided with information prepared by an independent consulting firm regarding Dreyfus’ approach to allocating costs to, and determining the profitability of, individual funds and the entire Dreyfus mutual fund complex.The Board members also had been informed that the methodology had been reviewed by an independent registered public accounting firm which, like the consultant, found the methodology to be reasonable. The consulting firm also analyzed where any economies of scale might emerge in connection with the management of the fund.The Board members evaluated the profitability analysis in light of the relevant circumstances for the fund and the extent to which economies of scale would be realized if the fund grows and whether fee levels reflect these economies of scale for the benefit of fund investors.The Board members also considered potential benefits to Dreyfus from acting as investment adviser and noted that there were no soft dollar arrangements with respect to trading the fund’s investments.

It was noted that the Board members should consider Dreyfus’ profitability with respect to the fund as part of their evaluation of whether the fees under the Management Agreement bear a reasonable relationship to the mix of services provided by Dreyfus, including the nature, extent and quality of such services and that a discussion of economies of scale is predicated on a fund having achieved a substantial size with increasing assets and that, if a fund’s assets had been static or decreasing, the possibility that Dreyfus may have realized any economies of scale would be less. It also was noted that the profitability percentage for managing the fund was within the range determined by appropriate court cases to be reasonable given the services rendered.The Board also noted fee waiver and expense reimbursement arrangements and the effect on Dreyfus’ profitability.

At the conclusion of these discussions, the Board agreed that it had been furnished with sufficient information to make an informed business decision with respect to re-approving the Management Agreement. Based on the discussions and considerations as described above, the Board made the following conclusions and determinations.

The Board concluded that the nature, extent and quality of the services provided by Dreyfus are adequate and appropriate.
The Board was satisfied with the fund's relative performance.
The Board concluded that the fee payable by the fund to Dreyfus was reasonable in light of the considerations described above.
The Board determined that the economies of scale which may accrue to Dreyfus and its affiliates in connection with the manage- ment of the fund had been adequately considered by Dreyfus in connection with the management fee rate charged to the fund and that, to the extent in the future it were determined that material economies of scale had not been shared with the fund, the Board would seek to have those economies of scale shared with the fund.

The Board members considered these conclusions and determinations, along with information received on a routine and regular basis throughout the year, and, without any one factor being dispositive, the Board determined that re-approval of the Management Agreement was in the best interests of the fund and its shareholders.


The Fund	23

OFFICERS OF THE FUND (Unaudited)

BRADLEY J. SKAPYAK, President since January 2010.

Chief Operating Officer and a director of the Manager since June 2009. From April 2003 to June 2009, Mr. Skapyak was the head of the Investment Accounting and Support Department of the Manager. He is an officer of 76 investment companies (comprised of 169 portfolios) managed by the Manager. He is 52 years old and has been an employee of the Manager since February 1988.

PHILLIP N. MAISANO, Executive Vice President since July 2007.

Chief Investment Officer,Vice Chair and a director of the Manager, and an officer of 76 investment companies (comprised of 169 portfolios) managed by the Manager. Mr. Maisano also is an officer and/or Board member of certain other investment management subsidiaries of The Bank of New York Mellon Corporation, each of which is an affiliate of the Manager. He is 63 years old and has been an employee of the Manager since November 2006. Prior to joining the Manager, Mr. Maisano served as Chairman and Chief Executive Officer of EACM Advisors, an affiliate of the Manager, since August 2004.

MICHAEL A. ROSENBERG, Vice President and Secretary since August 2005.

Assistant General Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 50 years old and has been an employee of the Manager since October 1991.

KIESHA ASTWOOD, Vice President and Assistant Secretary since January 2010.

Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. She is 37 years old and has been an employee of the Manager since July 1995.

JAMES BITETTO, Vice President and Assistant Secretary since August 2005.

Senior Counsel of BNY Mellon and Secretary of the Manager, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 44 years old and has been an employee of the Manager since December 1996.

JONI LACKS CHARATAN, Vice President and Assistant Secretary since August 2005.

Senior Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. She is 55 years old and has been an employee of the Manager since October 1988.

JOSEPH M. CHIOFFI, Vice President and Assistant Secretary since August 2005.

Senior Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 49 years old and has been an employee of the Manager since June 2000.

KATHLEEN DENICHOLAS, Vice President and Assistant Secretary since January 2010.

Senior Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. She is 36 years old and has been an employee of the Manager since February 2001.

JANETTE E. FARRAGHER, Vice President and Assistant Secretary since August 2005.

Assistant General Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. She is 48 years old and has been an employee of the Manager since February 1984.

JOHN B. HAMMALIAN, Vice President and Assistant Secretary since August 2005.

Managing Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 47 years old and has been an employee of the Manager since February 1991.

M. CRISTINA MEISER, Vice President and Assistant Secretary since December 2009.

Senior Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. She is 40 years old and has been an employee of the Manager since August 2001.

ROBERT R. MULLERY, Vice President and Assistant Secretary since August 2005.

Managing Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 58 years old and has been an employee of the Manager since May 1986.

JEFF PRUSNOFSKY, Vice President and Assistant Secretary since August 2005.

Managing Counsel of BNY Mellon, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 45 years old and has been an employee of the Manager since October 1990.

JAMES WINDELS, Treasurer since November 2001.

Director – Mutual Fund Accounting of the Manager, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 52 years old and has been an employee of the Manager since April 1985.

RICHARD CASSARO, Assistant Treasurer since January 2008.

Senior Accounting Manager – Money Market and Municipal Bond Funds of the Manager, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 51 years old and has been an employee of the Manager since September 1982.

GAVIN C. REILLY, Assistant Treasurer since August 2005.

Tax Manager of the Investment Accounting and Support Department of the Manager, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 42 years old and has been an employee of the Manager since April 1991.

ROBERT ROBOL, Assistant Treasurer since August 2005.

Senior Accounting Manager – Fixed Income Funds of the Manager, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 46 years old and has been an employee of the Manager since October 1988.

ROBERT SALVIOLO, Assistant Treasurer since July 2007.

Senior Accounting Manager – Equity Funds of the Manager, and an officer of 77 investment companies (comprised of 194 portfolios) managed by the Manager. He is 43 years old and has been an employee of the Manager since June 1989.


The Fund	27

OFFICERS OF THE FUND (Unaudited) (continued)

ROBERT SVAGNA, Assistant Treasurer since August 2005.

JOSEPH W. CONNOLLY, Chief Compliance Officer since October 2004.

Chief Compliance Officer of the Manager and The Dreyfus Family of Funds (77 investment companies, comprised of 194 portfolios). From November 2001 through March 2004, Mr. Connolly was first Vice-President, Mutual Fund Servicing for Mellon Global Securities Services. In that capacity, Mr. Connolly was responsible for managing Mellon’s Custody, Fund Accounting and Fund Administration services to third-party mutual fund clients. He is 53 years old and has served in various capacities with the Manager since 1980, including manager of the firm’s Fund Accounting Department from 1997 through October 2001.

NATALIA GRIBAS, Anti-Money Laundering Compliance Officer since July 2010.

Anti-Money Laundering Compliance Officer of the Distributor, and the Anti-Money Laundering Compliance Officer of 73 investment companies (comprised of 190 portfolios) managed by the Manager. She is 40 years old and has been an employee of the Distributor since September 2008.

For More Information

Telephone 1-800-645-6561

Mail The Dreyfus Family of Funds, 144 Glenn Curtiss Boulevard, Uniondale, NY 11556-0144 E-mail Send your request to info@dreyfus.com Internet Information can be viewed online or downloaded at: http://www.dreyfus.com

The fund will disclose daily, on www.dreyfus.com, the fund’s complete schedule of holdings as of the end of the previous business day. The schedule of holdings will remain on the website until the fund files its Form N-Q or Form N-CSR for the period that includes the date of the posted holdings.

The fund files its complete schedule of portfolio holdings with the Securities and Exchange Commission (“SEC”) for the first and third quarters of each fiscal year on Form N-Q. The fund's Forms N-Q are available on the SEC’s website at http://www.sec.gov and may be reviewed and copied at the SEC’s Public Reference Room in Washington, DC. Information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330.

Information regarding how the fund voted proxies relating to portfolio securities for the most recent 12-month period ended June 30 is available on the SEC’s website at http://www.sec.gov and without charge, upon request, by calling 1-800-645-6561.

Item 2. Code of Ethics.

The Registrant has adopted a code of ethics that applies to the Registrant's principal executive officer, principal financial officer, principal accounting officer or controller, or persons performing similar functions. There have been no amendments to, or waivers in connection with, the Code of Ethics during the period covered by this Report.

Item 3. Audit Committee Financial Expert.

The Registrant's Board has determined that David P. Feldman, a member of the Audit Committee of the Board, is an audit committee financial expert as defined by the Securities and Exchange Commission (the "SEC"). David P. Feldman is "independent" as defined by the SEC for purposes of audit committee financial expert determinations.

Item 4. Principal Accountant Fees and Services.

(a) Audit Fees. The aggregate fees billed for each of the last two fiscal years (the "Reporting Periods") for professional services rendered by the Registrant's principal accountant (the "Auditor") for the audit of the Registrant's annual financial statements or services that are normally provided by the Auditor in connection with the statutory and regulatory filings or engagements for the Reporting Periods, were $ 36,326 in 2009 and $36,326 in 2010.

(b) Audit-Related Fees. The aggregate fees billed in the Reporting Periods for assurance and related services by the Auditor that are reasonably related to the performance of the audit of the Registrant's financial statements and are not reported under paragraph (a) of this Item 4 were $$5,276 in 2009 and $5,376 in 2010. These services consisted of security counts required by Rule 17f-2 under the Investment Company Act of 1940, as amended.

The aggregate fees billed in the Reporting Periods for non-audit assurance and related services by the Auditor to the Registrant's investment adviser (not including any sub-investment adviser whose role is primarily portfolio management and is subcontracted with or overseen by another investment adviser), and any entity controlling, controlled by or under common control with the investment adviser that provides ongoing services to the Registrant ("Service Affiliates"), that were reasonably related to the performance of the annual audit of the Service Affiliate, which required pre-approval by the Audit Committee were $0 in 2009 and $0 in 2010.

(c) Tax Fees. The aggregate fees billed in the Reporting Periods for professional services rendered by the Auditor for tax compliance, tax advice, and tax planning ("Tax Services") were $3,638 in 2009 and $3,181 in 2010. These services consisted of: (i) review or preparation of U.S. federal, state, local and excise tax returns; (ii) U.S. federal, state and local tax planning, advice and assistance regarding statutory, regulatory or administrative developments; (iii) tax advice regarding tax qualification matters and/or treatment of various financial instruments held or proposed to be acquired or held. The aggregate fees billed in the Reporting Periods for Tax Services by the Auditor to Service Affiliates, which required pre-approval by the Audit Committee were $0 in 2009 and $0 in 2010.

(d) All Other Fees. The aggregate fees billed in the Reporting Periods for products and services provided by the Auditor, other than the services reported in paragraphs (a) through (c) of this Item, were $684 in 2009 and $367 in 2010. [These services consisted of a review of the Registrant's anti-money laundering program].

The aggregate fees billed in the Reporting Periods for Non-Audit Services by the Auditor to Service Affiliates, other than the services reported in paragraphs (b) through (c) of this Item, which required pre-approval by the Audit Committee, were $0 in 2009 and $0 in 2010.

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Note: None of the services described in paragraphs (b) through (d) of this Item 4 were approved by the Audit Committee pursuant to paragraph (c)(7)(i)(C) of Rule 2-01 of Regulation S-X.

Audit Committee Pre-Approval Policies and Procedures. The Registrant's Audit Committee has established policies and procedures (the "Policy") for pre-approval (within specified fee limits) of the Auditor's engagements for non-audit services to the Registrant and Service Affiliates without specific case-by-case consideration. Pre-approval considerations include whether the proposed services are compatible with maintaining the Auditor's independence. Pre-approvals pursuant to the Policy are considered annually.

Non-Audit Fees. The aggregate non-audit fees billed by the Auditor for services rendered to the Registrant, and rendered to Service Affiliates, for the Reporting Periods were $24,975,296 in 2009 and $39,552,052 in 2010.

Auditor Independence. The Registrant's Audit Committee has considered whether the provision of non-audit services that were rendered to Service Affiliates, which were not pre-approved (not requiring pre-approval), is compatible with maintaining the Auditor's independence.

Item 5. Audit Committee of Listed Registrants.

Not applicable. [CLOSED-END FUNDS ONLY]

Item 6. Investments.

(a) Not applicable.

Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End Management Investment Companies.

Not applicable. [CLOSED-END FUNDS ONLY]

Item 8. Portfolio Managers of Closed-End Management Investment Companies.

Not applicable. [CLOSED-END FUNDS ONLY, beginning with reports for periods ended on and after December 31, 2005]

Item 9. Purchases of Equity Securities by Closed-End Management Investment Companies and Affiliated Purchasers.

Not applicable. [CLOSED-END FUNDS ONLY]

Item 10. Submission of Matters to a Vote of Security Holders.

There have been no material changes to the procedures applicable to Item 10.

Item 11. Controls and Procedures.

(a) The Registrant's principal executive and principal financial officers have concluded, based on their evaluation of the Registrant's disclosure controls and procedures as of a date within 90 days of the filing date of this report, that the Registrant's disclosure controls and procedures are reasonably designed to ensure that information required to be disclosed by the Registrant on Form N-CSR is recorded, processed, summarized and reported within the required time periods and that information required to be disclosed by the Registrant in the reports that it files or submits on Form N-CSR is accumulated and communicated to the Registrant's management, including its principal executive and principal financial officers, as appropriate to allow timely decisions regarding required disclosure.

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(b) There were no changes to the Registrant's internal control over financial reporting that occurred during the second fiscal quarter of the period covered by this report that have materially affected, or are reasonably likely to materially affect, the Registrant's internal control over financial reporting.

Item 12. Exhibits.

(a)(1) Code of ethics referred to in Item 2.

(a)(2) Certifications of principal executive and principal financial officers as required by Rule 30a-2(a) under the Investment Company Act of 1940.

(a)(3) Not applicable.

(b) Certification of principal executive and principal financial officers as required by Rule 30a-2(b) under the Investment Company Act of 1940.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the Registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized.

Dreyfus 100% U.S. Treasury Money Market Fund

By: /s/Bradley J. Skapyak
Bradley J. Skapyak, President
Date:	February 23, 2011

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this Report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated.

By: /s/Bradley J. Skapyak
Bradley J. Skapyak, President
Date:	February 23, 2011

By: /s/ James Windels
James Windels, Treasurer
Date:	February 23, 2011

EXHIBIT INDEX

(a)(1) Code of ethics referred to in Item 2.

(a)(2) Certifications of principal executive and principal financial officers as required by Rule 30a-2(a) under the Investment Company Act of 1940. (EX-99.CERT)

(b) Certification of principal executive and principal financial officers as required by Rule 30a-2(b) under the Investment Company Act of 1940. (EX-99.906CERT)

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