485BPOS

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM N-1A
REGISTRATION STATEMENT (No. 002-62417)
		UNDER THE SECURITIES ACT OF 1933	[X]
		Pre-Effective Amendment No. ____	[ ]
		Post-Effective Amendment No. 77	[X]
and
REGISTRATION STATEMENT (No. 811-02861)
		UNDER THE INVESTMENT COMPANY ACT OF 1940	[X]
		Amendment No. 77	[X]
Fidelity Money Market Trust
(Exact Name of Registrant as Specified in Charter)
82 Devonshire St., Boston, Massachusetts 02109
(Address Of Principal Executive Offices) (Zip Code)
Registrant's Telephone Number: 617-563-7000
Scott C. Goebel, Secretary
82 Devonshire Street
Boston, Massachusetts 02109
(Name and Address of Agent for Service)
It is proposed that this filing will become effective
	(X)	immediately upon filing pursuant to paragraph (b).
	( )	on ( ) pursuant to paragraph (b) at 5:30 p.m. Eastern Time.
	( )	60 days after filing pursuant to paragraph (a)(1) at 5:30 p.m. Eastern Time.
	( )	on ( ) pursuant to paragraph (a)(1) of Rule 485 at 5:30 p.m. Eastern Time.
	( )	75 days after filing pursuant to paragraph (a)(2) at 5:30 p.m. Eastern Time.
	( )	on ( ) pursuant to paragraph (a)(2) of Rule 485 at 5:30 p.m. Eastern Time.
If appropriate, check the following box:
	( )	this post-effective amendment designates a new effective date for a previously filed post-effective amendment.

EXHIBIT INDEX

Exhibit	Exhibit No.
XBRL Instance Document	EX-101.INS
XBRL Taxonomy Extension Schema Document	EX-101.SCH
XBRL Taxonomy Extension Calculation Linkbase Document	EX-101.CAL
XBRL Taxonomy Extension Definition Linkbase Document	EX-101.DEF
XBRL Taxonomy Extension Labels Linkbase Document	EX-101.LAB
XBRL Taxonomy Extension Presentation Linkbase Document	EX-101.PRE

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for the effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment No. 77 to the Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Boston, and Commonwealth of Massachusetts, on the 15th day of November 2012.

	Fidelity Money Market Trust
	By	/s/John R. Hebble
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||		John R. Hebble, President

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

(Signature)		(Title)	(Date)
/s/John R. Hebble		President and Treasurer	November 15, 2012
John R. Hebble		(Principal Executive Officer)
/s/Christine Reynolds		Chief Financial Officer	November 15, 2012
Christine Reynolds		(Principal Financial Officer)
/s/Abigail P. Johnson		Trustee	November 15, 2012
Abigail P. Johnson
/s/James C. Curvey	*	Trustee	November 15, 2012
James C. Curvey
/s/Albert R. Gamper	*	Trustee	November 15, 2012
Albert R. Gamper
/s/Robert F. Gartland	*	Trustee	November 15, 2012
Robert F. Gartland
/s/Arthur E. Johnson	*	Trustee	November 15, 2012
Arthur E. Johnson
/s/Michael E. Kenneally	*	Trustee	November 15, 2012
Michael E. Kenneally
/s/James H. Keyes	*	Trustee	November 15, 2012
James H. Keyes
/s/Marie L. Knowles	*	Trustee	November 15, 2012
Marie L. Knowles
/s/Kenneth L. Wolfe	*	Trustee	November 15, 2012
Kenneth L. Wolfe

*	By:	/s/Joseph R. Fleming
		Joseph R. Fleming, pursuant to a power of attorney dated February 1, 2011 and filed herewith.

POWER OF ATTORNEY

We, the undersigned Directors or Trustees, as the case may be, of the following investment companies:

  Fidelity Aberdeen Street Trust Fidelity Advisor Series II Fidelity Advisor Series IV Fidelity Boylston Street Trust Fidelity California Municipal Trust Fidelity California Municipal Trust II Fidelity Central Investment Portfolios II LLC Fidelity Charles Street Trust Fidelity Colchester Street Trust Fidelity Court Street Trust Fidelity Court Street Trust II Fidelity Fixed-Income Trust Fidelity Garrison Street Trust Fidelity Hereford Street Trust Fidelity Income Fund   Fidelity Massachusetts Municipal Trust Fidelity Money Market Trust Fidelity Municipal Trust Fidelity Municipal Trust II Fidelity Newbury Street Trust Fidelity New York Municipal Trust Fidelity New York Municipal Trust II Fidelity Oxford Street Trust Fidelity Phillips Street Trust Fidelity Revere Street Trust Fidelity School Street Trust Fidelity Union Street Trust Fidelity Union Street Trust II Variable Insurance Products Fund V

in addition to any other investment company for which Fidelity Management & Research Company ("FMR") or an affiliate acts as investment adviser and for which the undersigned individuals serve as Directors or Trustees (collectively, the "Funds"), hereby revoke all previous powers of attorney we have given to sign and otherwise act in our names and behalf in matters involving any investment company for which FMR or an affiliate acts as investment adviser and hereby constitute and appoint Thomas C. Bogle, Joseph R. Fleming, John V. O'Hanlon, Robert W. Helm and Anthony H. Zacharski, each of them singly, our true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for us and in our names in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, or any successors thereto, any and all subsequent Amendments, Pre-Effective Amendments, or Post-Effective Amendments to said Registration Statements or any successors thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in our names and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940, and all related requirements of the Securities and Exchange Commission. We hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof. This power of attorney is effective for all documents filed on or after February 1, 2011.

WITNESS our hands on this first day of February 1, 2011.

/s/James C. Curvey	/s/Michael E. Kenneally
James C. Curvey	Michael E. Kenneally
/s/Albert R. Gamper, Jr.	/s/James H. Keyes
Albert R. Gamper, Jr.	James H. Keyes
/s/Robert F. Gartland	/s/Marie L. Knowles
Robert F. Gartland	Marie L. Knowles
/s/Arthur E. Johnson	/s/Kenneth L. Wolfe
Arthur E. Johnson	Kenneth L. Wolfe

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Retirement Government Money Market Portfolio

Fund Summary

Fund:
Retirement Government Money Market Portfolio

Investment Objective

The fund seeks as high a level of current income as is consistent with the security of principal and liquidity.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Retirement Government Money Market Portfolio Class: Retirement Government Money Market Portfolio
Shareholder fees (fees paid directly from your investment)	none

Annual fund operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Fund Operating Expenses	Retirement Government Money Market Portfolio Class: Retirement Government Money Market Portfolio
Management fee	0.42%
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual fund operating expenses	0.42%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Retirement Government Money Market Portfolio Class: Retirement Government Money Market Portfolio
1 year	43
3 years	135
5 years	235
10 years	530

Principal Investment Strategies

• Normally investing at least 80% of assets in U.S. Government securities and repurchase agreements for those securities.
• Investing in U.S. Government securities issued by entities that are chartered or sponsored by Congress but whose securities are neither issued nor guaranteed by the U.S. Treasury.
• Potentially entering into reverse repurchase agreements.
• Investing in compliance with industry-standard regulatory requirements for money market funds for the quality, maturity, and diversification of investments.

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a money market security to decrease.
• Issuer-Specific Changes. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a money market security to decrease.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation 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.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year. Past performance is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	1.26%	December 31, 2006
Lowest Quarter Return	0.00%	March 31, 2010
Year-to-Date Return	0.01%	September 30, 2012

Average Annual Returns
For the periods ended
December 31, 2011

Average Annual Total Returns	Past 1 year	Past 5 years	Past 10 years
Retirement Government Money Market Portfolio Class: Retirement Government Money Market Portfolio	0.01%	1.51%	1.85%