UNITED STATES SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 11-K

(Mark One)

þ ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2006

OR

o TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from ____________________ to ____________________

Commission file number 0-27058

PAREXEL International Corporation 401(k) Retirement Savings Plan
(Full Title of the Plan)

PAREXEL International Corporation
200 West Street
Waltham, MA 02451
(Name of Issuer of the Securities Held Pursuant to the
Plan and the Address of its Principal Executive Offices)

Audited Financial Statements and
Supplemental Schedule

PAREXEL International Corporation 401(k) Retirement Savings Plan
Year Ended December 31, 2006
With Report of Independent Auditors

PAREXEL International Corporation 401(k) Retirement Savings Plan

Audited Financial Statements and Supplemental Schedule

Year Ended December 31, 2006

Contents

Report of Independent Registered Public Accounting Firm	1
Audited Financial Statements
Statements of Net Assets Available for Benefits	2
Statement of Changes in Net Assets Available for Benefits	3
Notes to Financial Statements	4
Supplemental Schedule
Schedule H, Line 4i — Schedule of Assets (Held at End of Year)	8
EX-23 Consent of Independent Registered Public Accounting Firm

Report of Independent Registered Public Accounting Firm

The Plan Administrator and Participants
PAREXEL International Corporation 401(k) Retirement Savings Plan

We have audited the accompanying statements of net assets available for benefits of the PAREXEL International Corporation 401(k) Retirement Savings Plan as of December 31, 2006 and 2005, and the related statement of changes in net assets available for benefits for the year ended December 31, 2006. These financial statements are the responsibility of the Plan’s management. Our responsibility is to express an opinion on these financial statements 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 are free of material misstatement. We were not engaged to perform an audit of the Plan’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 Plan’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, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

In our opinion, the financial statements referred to above present fairly, in all material respects, the net assets available for benefits of the Plan at December 31, 2006 and 2005, and the changes in its net assets available for benefits for the year ended December 31, 2006, in conformity with U.S. generally accepted accounting principles.

Our audits were performed for the purpose of forming an opinion on the financial statements taken as a whole. The accompanying supplemental schedule of assets (held at end of year) as of December 31, 2006 is presented for purposes of additional analysis and is not a required part of the financial statements, but is supplementary information required by the Department of Labor’s Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. The supplemental schedule is the responsibility of the Plan’s management. The supplemental schedule has been subjected to the auditing procedures applied in our audits of financial statements and, in our opinion, is fairly stated in all material respects in relation to the financial statements taken as a whole.

/s/ ERNST & YOUNG LLP

June 19, 2007

1

PAREXEL International Corporation 401(k) Retirement Savings Plan

Statements of Net Assets Available for Benefits

	December 31
	2006		2005
Assets
Investments, at fair value:
Fidelity Contrafund	$	13,704,956	$	11,989,078
Fidelity Magellan Fund		12,585,580		12,560,313
Fidelity Diversified International Fund		12,162,277		9,463,898
Fidelity Blue Chip Growth Fund		9,368,559		10,021,027
Fidelity Fund		7,599,527		7,304,448
Fidelity Asset Manager Portfolio		4,847,426		4,917,198
Fidelity Balanced Fund		4,458,370		3,268,904
Fidelity Retirement Money Market Portfolio		4,221,240		3,816,417
Fidelity Intermediate Bond Fund		4,043,260		3,877,384
Fidelity Low-Priced Stock Fund		1,913,762		1,622,681
Fidelity Small Cap Stock Fund		1,888,187		1,069,947
Artisan Mid Cap Fund		1,780,653		1,229,275
Oakmark Fund		1,439,903		1,005,184
Fidelity Freedom 2030 Fund		1,132,613		882,952
Fidelity Freedom 2020 Fund		1,015,317		797,297
Fidelity Freedom 2040 Fund		818,164		519,934
Fidelity Freedom 2010 Fund		802,367		717,462
Fidelity Freedom 2025 Fund		432,705		126,199
Fidelity Freedom 2015 Fund		405,442		249,710
Fidelity Freedom Income Fund		405,132		295,525
Fidelity Freedom 2035 Fund		286,845		146,073
PAREXEL International Stock Fund		284,039		134,601
Fidelity Freedom 2000 Fund		191,637		172,091
Fidelity Freedom 2005 Fund		31,962		10,289
Fidelity Cash Reserves Fund		108		49
Participant loans		868,745		806,476
Total investments		86,688,776		77,004,412
Receivables:
Participants’ contributions		266,418		259,616
Employer contribution		73,088		72,629
Total receivables		339,506		332,245
Net assets available for benefits	$	87,028,282	$	77,336,657

See accompanying notes.

2

PAREXEL International Corporation 401(k) Retirement Savings Plan

Statement of Changes in Net Assets Available for Benefits

Year Ended December 31, 2006

Additions
Contributions:
Participants	$	8,060,255
Employer		1,867,554
Rollovers		1,286,700
		11,214,509
Net appreciation in fair value of investments		1,074,056
Dividends and interest income		7,416,300
Total additions		19,704,865
Deductions
Benefits paid directly to participants		9,976,738
Administrative expenses		36,502
Total deductions		10,013,240
Net increase		9,691,625
Net assets available for benefits at beginning of year		77,336,657
Net assets available for benefits at end of year	$	87,028,282

See accompanying notes.

3

PAREXEL International Corporation 401(k) Retirement Savings Plan

Notes to Financial Statements

December 31, 2006

1.   Description of the Plan

The following description of the PAREXEL International Corporation (the Company or Plan Sponsor) 401(k) Retirement Savings Plan (the Plan) provides only general information. Participants should refer to the Plan Agreement for a more complete description of the Plan’s provisions.

General

The Plan is a defined contribution 401(k) profit sharing plan established effective January 1, 1988. It is subject to the provisions of the Internal Revenue Code of 1986, as amended, (the Code) and the Employee Retirement Income Security Act of 1974 (ERISA).

The Plan covers all full-time, part-time, and temporary employees of the Company who are age 21 years or older.

On November 16, 2006, the Company acquired California Clinical Trials Medical Group, Inc. Effective May 1, 2007, the California Clinical Trials 401(k) Plan was merged into the Plan. Subsequently, total plan assets amounting to $1,353,678 were transferred into the Plan.

Contributions

Participants may contribute up to 60% of their annual compensation, as defined and including 100% of cash bonuses, subject to Internal Revenue Service (IRS) limitations. Participants may also contribute amounts representing distributions from other qualified defined benefit or defined contribution plans.

The Company matches an amount equal to 100% of the first 3% of compensation contributed by each participant, not to exceed $3,000 per participant per annum. In addition, the Company may make a discretionary contribution to be allocated to eligible participants in the ratio that each eligible participant’s compensation bears to the total compensation paid to all eligible participants for the plan year. During the plan year ended December 31, 2006, no discretionary contribution was made to the Plan by the Company.

4

PAREXEL International Corporation 401(k) Retirement Savings Plan

Notes to Financial Statements (continued)

1.   Description of the Plan (continued)

Participant Accounts

Participant accounts are maintained by an independent recordkeeper, Fidelity Retirement Investment Services. Each participant’s account is credited with the participant’s contributions, Company matching contributions, an allocation of Plan earnings (losses), and is charged with an allocation of administrative expenses, as applicable. The benefit to which a participant is entitled is the benefit that can be provided from the participant’s account.

Vesting

Participants are immediately vested in their voluntary contributions, plus actual earnings thereon. Vesting in Company contributions and earnings thereon is based on years of continuous service. Each participant vests in 20% increments for each of the first five years of credited service, as defined.

Forfeitures of terminated participants’ nonvested accounts can be used to reduce future Company contributions to the Plan, and pay for the Plan’s administrative fees. During the year ended December 31, 2006, forfeitures used to offset Company contributions amounted to $469,547, and $26,706 was used to pay administrative fees. At December 31, 2006 and 2005, forfeited nonvested amounts available to offset future Company contributions amounted to $218,145 and $156,472, respectively.

Participant Loans

A participant may borrow from his or her account a minimum of $1,000, not to exceed the lesser of $50,000 or 50% of his or her vested account balance. Loans are secured by the balance in the participant’s account and bear interest at a rate commensurate with local market rates for similar loans. Loans must be repaid within five years, unless the loan is for the purchase of a primary residence, in which case it is repayable in ten years. Principal and interest are paid ratably through payroll deductions.

Benefits

A participant’s account is payable in a lump-sum amount equal to the vested value of his or her account upon termination of service, retirement or early retirement, if elected, death, permanent or total disability, or age 59 1/2. In-service withdrawals may be made in the event of a financial hardship, yet will result in the suspension of all contributions for 12 months.

5

PAREXEL International Corporation 401(k) Retirement Savings Plan

Notes to Financial Statements (continued)

1.   Description of the Plan (continued)

Plan Termination

Although it has not expressed any intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and to terminate the Plan subject to the provisions of ERISA. In the event of a Plan termination, participants will become 100% vested in their accounts.

2.   Summary of Significant Accounting Policies

Basis of Accounting

The financial statements have been prepared on the accrual basis of accounting.

Investment Valuation and Income Recognition

Investments in mutual funds are valued at quoted market prices, which represent the net asset value of shares held by the Plan at year end. The Company stock is valued based upon quoted market prices. Participant loans are valued at their outstanding balances, which approximate fair value.

Security transactions are accounted for on a trade-date basis, and realized gains and losses on investments are calculated as the difference between the cost of the investment shares sold and the market value of the shares sold. The net appreciation in the fair value of investments reported in the statement of changes in net assets available for benefits includes realized and unrealized gains and losses on investments. Investment income is recorded on the accrual basis. Dividends are recorded as of the ex-dividend date.

Use of Estimates

The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

Expenses

All Plan expenses are paid by the Company, except those relating to recordkeeping fees on participant loans, which are allocated to the individual participants’ accounts.

6

PAREXEL International Corporation 401(k) Retirement Savings Plan

Notes to Financial Statements (continued)

3.   Investments

During the year ended December 31, 2006, the Plan’s investments (including investments bought, sold, and held during the year) appreciated in value as follows:

Mutual funds	$	1,015,568
PAREXEL International Stock Fund		58,488
Net appreciation in fair value of investments	$	1,074,056

4.   Risks and Uncertainties

The Plan and its participants invest in various investment securities. Investment securities are exposed to various risks such as interest rate, market, and credit risks. Due to the level of risk associated with certain investment securities, it is at least reasonably possible that changes in the values of investment securities will occur in the near term, and that such changes could materially affect participants’ account balances and the amounts reported in the statements of net assets available for benefits.

5.   Income Tax Status

The underlying nonstandardized prototype plan has received an opinion letter from the Internal Revenue Service (IRS), dated December 5, 2001, stating that the form of the Plan is qualified under Section 401 of the Internal Revenue Code, and therefore, the related trust is tax exempt. In accordance with Revenue Procedure 2007-6 and Announcement 2001-77, the Plan Sponsor has determined that it is eligible to, and has chosen to, rely on the current IRS prototype plan opinion letter. Once qualified, the Plan is required to operate in conformity with the Code to maintain its qualification. The plan administrator believes the Plan is being operated in compliance with the applicable requirements of the Code and, therefore, believes that the Plan is qualified and the related trust is tax exempt.

7

Supplemental Schedule

PAREXEL International Corporation 401(k) Retirement Savings Plan

Schedule H, Line 4i — Schedule of Assets (Held at End of Year)

EIN No. 04-2776269 Plan No. 001

December 31, 2006

	Description of Investment,
	Including Maturity Date,
	Rate of Interest,
Identity of Issuer, Borrower,	Collateral, Par, or	Current
Lessor, or Similar Party	Maturity Value	Value
*Fidelity Contrafund	210,199 shares	$	13,704,956
*Fidelity Magellan Fund	140,590 shares		12,585,580
*Fidelity Diversified International Fund	329,155 shares		12,162,277
*Fidelity Blue Chip Growth Fund	211,432 shares		9,368,559
*Fidelity Fund	212,040 shares		7,599,527
*Fidelity Asset Manager Portfolio	300,895 shares		4,847,426
*Fidelity Balanced Fund	229,458 shares		4,458,370
*Fidelity Retirement Money Market Portfolio	4,221,240 shares		4,221,240
*Fidelity Intermediate Bond Fund	394,080 shares		4,043,260
*Fidelity Low-Priced Stock Fund	43,954 shares		1,913,762
*Fidelity Small Cap Stock Fund	99,326 shares		1,888,187
Artisan Mid Cap Fund	58,459 shares		1,780,653
Oakmark Fund	31,357 shares		1,439,903
*Fidelity Freedom 2030 Fund	70,656 shares		1,132,613
*Fidelity Freedom 2020 Fund	65,378 shares		1,015,317
*Fidelity Freedom 2040 Fund	86,304 shares		818,164
*Fidelity Freedom 2010 Fund	54,881 shares		802,367
*Fidelity Freedom 2025 Fund	33,884 shares		432,705
*Fidelity Freedom 2015 Fund	33,233 shares		405,442
*Fidelity Freedom Income Fund	35,107 shares		405,132
*Fidelity Freedom 2035 Fund	21,747 shares		286,845
*PAREXEL International Stock Fund	9,805 shares		284,039
*Fidelity Freedom 2000 Fund	15,380 shares		191,637
*Fidelity Freedom 2005 Fund	2,753 shares		31,962
*Fidelity Cash Reserve Fund	108 shares		108
*Participant loans	5% to 10%		868,745
		$	86,688,776

* Indicates party-in-interest to the Plan.

Note: Cost information has not been included because all investments are participant directed.

8

Signatures

Pursuant to the requirements of the Securities and Exchange Act of 1934, the PAREXEL International Corporation 401(k) Retirement Savings Plan has duly caused this annual report to be signed on its behalf by the undersigned hereto duly authorized.

Date: June 20, 2007	By:	/s/ Michael Brandt
		Michael Brandt
		Vice President, Human Resources

Index to Exhibits

Exhibit No.
23	Consent of Independent Registered Public Accounting Firm