UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington D.C. 20549

Form 6-K

REPORT OF FOREIGN ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

OF THE SECURITIES EXCHANGE ACT OF 1934

For the month of May 2013

Commission File Number: 001-33623

WuXi PharmaTech (Cayman) Inc.

288 Fute Zhong Road, Waigaoqiao Free Trade Zone

Shanghai 200131

People’s Republic of China

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F. Form 20-F  x Form 40-F  ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ¨

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.    Yes  ¨    No  x

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):82- N/A

WuXi PharmaTech (Cayman) Inc.

Form 6-K

TABLE OF CONTENTS

	Page
Signature		3
Exhibit 99.1 — Press Release Dated May 13, 2013		4

2

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

WuXi PharmaTech (Cayman) Inc.
By:	/s/ Edward Hu
Name:	Edward Hu
Title:	Chief Financial Officer

Date: May 23, 2013

3

Exhibit 99.1

WuXi PharmaTech Announces First-Quarter 2013 Results

SHANGHAI, China, May 13, 2013 /Xinhua-PRNewswire/ — WuXi PharmaTech (Cayman) Inc. (NYSE: WX), a leading research and development outsourcing company serving the pharmaceutical, biotechnology, and medical device industries, with operations in China and the United States, today announced its financial results for the first quarter of 2013.

Highlights

• Net Revenues Increased 11.7% Year Over Year to $131.9 Million

• Laboratory Services Net Revenues Grew 12.5% Year Over Year to $97.5 Million

• China-Based Laboratory Services Net Revenues Increased 15.5% Year Over Year to $74.5 Million

• U.S.-Based Laboratory Services Net Revenues Increased 3.8% Year Over Year to $23.0 Million

• Manufacturing Services Net Revenues Grew 9.6% Year Over Year to $34.4 Million

• GAAP Diluted Earnings Per ADS Grew 7.2% Year Over Year to $0.30

• Non-GAAP Diluted Earnings Per ADS Increased 7.5% Year Over Year to $0.35

• Company Reconfirms Full-Year 2013 Guidance

Management Comment

“I am pleased to announce that WuXi began 2013 with a solid first quarter,” said Dr. Ge Li, Chairman and Chief Executive Officer. “We achieved 11.7% year-over-year revenue growth, 7.2% GAAP diluted EPS growth, and 7.5% non-GAAP diluted EPS growth in the quarter, exceeding our previous guidance in all three measures. This result gives us confidence to reconfirm our guidance for full-year 2013.

“WuXi is succeeding on several fronts at once,” Dr. Li continued. “We are achieving double-digit, broad-based revenue growth, while effectively improving operating efficiency and controlling our costs to maintain stable margins. We are investing in capabilities and capacity to sustain strong revenue and earnings growth for years to come. In so doing, WuXi is making progress toward the goal of building an open-access technology platform and integrated services offerings that will enable anyone and any company to discover and develop medicines efficiently and cost-effectively. And we are returning capital to shareholders through share purchases.”

First-Quarter 2013 GAAP Results

First-quarter 2013 net revenues increased 11.7% year over year to $131.9 million. Revenue growth in Laboratory Services of 12.5% was driven by our comprehensive and integrated discovery and development services, primarily in China. Revenue growth of 9.6% in Manufacturing Services was driven by increased demand for clinical-trial materials in our small molecule research manufacturing business and process-chemistry services. We also began biologics manufacturing in the first quarter.

First-quarter 2013 GAAP gross profit increased 13.2% year over year to $47.4 million due to 11.7% revenue growth, improved operating efficiency, and effective cost control. Gross margin increased year over year to 36.0% from 35.5%. Gross margin in Laboratory Services increased year over year to 37.6% from 37.1% mainly due to improved productivity, partially offset by the effects of increasing labor costs in China, appreciation of the RMB versus the U.S. dollar, investments in new businesses, and lower pricing in synthetic chemistry services. Gross margin in Manufacturing Services increased year over year to 31.4% from 31.0%.

First-quarter 2013 GAAP operating income increased 11.4% year over year to $23.0 million due to the 13.2% increase in gross profit, offset by a 14.8% increase in operating expenses, particularly selling and marketing expenses and research and development expenses. Operating margin decreased slightly to 17.4% from 17.5% due to the increase in operating expenses, partially offset by higher gross margin.

4

First-quarter 2013 GAAP net income increased 3.4% year over year to $21.7 million due to the 11.4% year-over-year increase in operating income, offset by a 39.9% increase in income tax expense primarily due to the increase in taxable income and the one-time benefit of reversal of an uncertain tax provision in the first quarter of 2012.

First-quarter 2013 GAAP diluted earnings per ADS increased 7.2% to $0.30 due to the 3.4% increase in net income and a lower number of outstanding ADSs as a result of the company’s purchase of about 5 million ADSs in 2012. First-quarter 2013 GAAP comprehensive income increased 8.8% year over year to $23.3 million due to the increase in currency translation adjustments and the 3.4% increase in GAAP net income.

First-Quarter 2013 Non-GAAP Results

Non-GAAP financial results exclude the impact of share-based compensation expenses and the amortization of acquired intangible assets and the associated deferred tax impact.

First-quarter 2013 non-GAAP gross profit increased 11.6% year over year to $48.5 million, mainly due to the broad-based revenue growth discussed above. Non-GAAP gross margin was flat year-over-year at 36.8%, as the benefits of improved productivity were fully offset by the effects of increasing labor costs in China, appreciation of the RMB versus the U.S. dollar, investments in new businesses, and lower pricing in synthetic chemistry services.

First-quarter 2013 non-GAAP operating income increased 9.8% year over year to $26.7 million, primarily due to the 11.6% increase in non-GAAP gross profit, partially offset by higher operating expenses, particularly selling and marketing expenses and research and development expenses. Operating margin decreased slightly to 20.2% from 20.6% due to this increase in operating expenses.

First-quarter 2013 non-GAAP net income grew 3.7% year over year to $25.4 million due to the 9.8% increase in non-GAAP operating income, offset by higher income tax expense primarily due to the increase in taxable income and the reversal of an uncertain tax provision in the first quarter of 2012.

First-quarter 2013 non-GAAP diluted earnings per ADS grew 7.5% year over year to $0.35 due to the 3.7% increase in net income and a lower number of outstanding ADSs as a result of share buybacks in 2012.

Full-Year 2013 Financial Guidance

The company reconfirms the following full-year 2013 financial guidance:

• Total net revenues of $565-575 million, or 13-15% year-over-year growth

• GAAP diluted earnings per ADS of $1.26-$1.30

• Non-GAAP diluted earnings per ADS of $1.49-$1.53

• Capital expenditures of about $60 million

The company provides the following new full-year 2013 financial guidance:

• GAAP and non-GAAP gross margin and operating margin comparable to those in 2012

Second-Quarter 2013 Financial Guidance

The company provides the following second-quarter 2013 financial guidance:

• Total net revenues of $138-140 million

• GAAP diluted earnings per ADS of $0.34-$0.35

• Non-GAAP diluted earnings per ADS of $0.39-$0.40

5

WUXI PHARMATECH (CAYMAN) INC.

UNAUDITED CONSOLIDATED BALANCE SHEETS

(in thousands of U.S. dollars, except ordinary share, ADS and par value data)

	March 31, 2013		December 31, 2012
Assets:
Current assets:
Cash and cash equivalents		104,899		54,133
Restricted cash		2,964		423
Short-term investments		160,754		175,245
Accounts receivable, net		98,790		99,578
Inventories		43,652		47,774
Prepaid expenses and other current assets		27,326		18,807
Total current assets		438,385		395,960
Non-current assets:
Goodwill		32,566		32,561
Property, plant and equipment, net		258,992		264,381
Long-term investments		15,797		14,015
Intangible assets, net		7,595		7,268
Land use rights		5,549		5,564
Deferred tax assets		3,045		3,037
Other non-current assets		15,726		19,749
Total non-current assets		339,270		346,575
Total assets		777,655		742,535
Liabilities and equity:
Current liabilities:
Short-term and current portion of long-term debt		62,283		59,089
Accounts payable		20,952		21,808
Accrued expenses		16,937		27,411
Deferred revenue		20,581		17,052
Advanced subsidies		10,798		9,265
Other taxes payable		3,593		1,581
Other current liabilities		20,790		11,215
Total current liabilities		155,934		147,421
Non-current liabilities:
Long-term debt, excluding current portion		5,643		5,697
Advanced subsidies		2,050		2,663
Long-term payables		758		732
Other non-current liabilities		7,659		7,799
Total non-current liabilities		16,110		16,891
Total liabilities		172,044		164,312
Equity:
Ordinary shares ($0.02 par value, 5,002,550,000 authorized, 561,121,002 and 566,540,378 issued and outstanding as of December 31, 2012, and March 31, 2013, respectively)		11,331		11,222
Additional paid-in capital		335,662		331,714
Retained earnings		210,316		188,604
Accumulated other comprehensive income		48,302		46,683
Total equity		605,611		578,223
Total liabilities and equity		777,655		742,535

6

WUXI PHARMATECH (CAYMAN) INC.

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(In thousands of U.S. dollars, except ADS data and per ADS data)

	Three Months Ended March 31,
	2013			2012			% Change
Net revenues:
Laboratory Services		97,481			86,650			12.5	%
Manufacturing Services		34,384			31,378			9.6	%
Total net revenues		131,865			118,028			11.7	%
Cost of revenues:
Laboratory Services		(60,875	)		(54,488	)		11.7	%
Manufacturing Services		(23,584	)		(21,649	)		8.9	%
Total cost of revenues		(84,459	)		(76,137	)		10.9	%
Gross profit:
Laboratory Services		36,606			32,162			13.8	%
Manufacturing Services		10,800			9,729			11.0	%
Total gross profit		47,406			41,891			13.2	%
Operating expenses:
Selling and marketing expenses		(3,931	)		(3,279	)		19.9	%
General and administrative expenses		(18,208	)		(16,162	)		12.7	%
Research and development expenses		(2,270	)		(1,813	)		25.2	%
Total operating expenses		(24,409	)		(21,254	)		14.8	%
Operating income		22,997			20,637			11.4	%
Other income (expenses), net:
Equity in earnings of joint ventures		(217	)		—			—
Other income (expenses), net		3,057			2,740			11.6	%
Interest income (expenses), net		1,594			1,699			(6.2	%)
Total other income (expenses), net		4,434			4,439			(0.1	%)
Income before income taxes		27,431			25,076			9.4	%
Income tax expense		(5,719	)		(4,088	)		39.9	%
Net income		21,712			20,988			3.4	%
Other comprehensive income:
Currency translation adjustments		1,620			454			256.8	%
Comprehensive income		23,332			21,442			8.8	%
Basic net earnings per ADS		0.31			0.29			5.8	%
Diluted net earnings per ADS		0.30			0.28			7.2	%
Weighted average ADS outstanding—basic		70,368,616			71,978,914			(2.2	%)
Weighted average ADS outstanding—diluted		71,915,069			74,543,632			(3.5	%)

7

WUXI PHARMATECH (CAYMAN) INC.

RECONCILIATION OF GAAP TO NON-GAAP

(in thousands of U.S. dollars, except ADS data and per ADS data)

	Three Months Ended March 31,
	2013			2012			% Change
GAAP gross profit		47,406			41,891			13.2	%
GAAP gross margin		36.0	%		35.5	%
Adjustments:
Share-based compensation		1,038			1,066			(2.6	%)
Amortization of acquired intangible assets		98			525			(81.3	%)
Non-GAAP gross profit		48,542			43,482			11.6	%
Non-GAAP gross margin		36.8	%		36.8	%
GAAP operating income		22,997			20,637			11.4	%
GAAP operating margin		17.4	%		17.5	%
Adjustments:
Share-based compensation		3,600			3,155			14.1	%
Amortization of acquired intangible assets		98			525			(81.3	%)
Non-GAAP operating income		26,695			24,317			9.8	%
Non-GAAP operating margin		20.2	%		20.6	%
GAAP net income		21,712			20,988			3.4	%
GAAP net margin		16.5	%		17.8	%
Adjustments:
Share-based compensation		3,600			3,155			14.1	%
Amortization of acquired intangible assets		98			525			(81.3	%)
Deferred tax impact related to acquired intangible assets		(29	)		(195	)		(85.1	%)
Non-GAAP net income		25,381			24,473			3.7	%
Non-GAAP net margin		19.2	%		20.7	%
Income attributable to holders of ADS (Non-GAAP):
Basic		25,381			24,473			3.7	%
Diluted		25,381			24,473			3.7	%
Basic earnings per ADS (Non-GAAP)		0.36			0.34			6.1	%
Diluted earnings per ADS (Non-GAAP)		0.35			0.33			7.5	%
Weighted average ADS outstanding – basic (Non-GAAP)		70,368,616			71,978,914			(2.2	%)
Weighted average ADS outstanding – diluted (Non-GAAP)		71,915,069			74,543,632			(3.5	%)

8

WUXI PHARMATECH (CAYMAN) INC.

REVENUE BREAKDOWN

(in thousands of U.S. dollars)

	Three Months Ended March 31,
	2013		2012		% Change
Net revenues:
China-based Laboratory Services		74,444		64,452		15.5	%
China-based Manufacturing Services		34,384		31,378		9.6	%
Subtotal		108,828		95,830		13.6	%
U.S.-based Laboratory Services		23,037		22,198		3.8	%
Total net revenues		131,865		118,028		11.7	%

Conference Call

WuXi PharmaTech senior management will host a conference call at 8:00 am (U.S. Eastern) / 5:00 am (U.S. Pacific) / 8:00 pm (Beijing/Shanghai/Hong Kong) on Tuesday, May 14, 2013, to discuss its first-quarter 2013 financial results and future prospects. The conference call may be accessed by calling:

United States:	1-866-519-4004
China (Landline):	800-819-0121
China (Mobile):	400-620-8038
Hong Kong:	800-930-346
United Kingdom:	0-808-234-6646
International:	+65-6723-9381
Conference ID:	35582613

A telephone replay will be available two hours after the call’s completion at:

United States:	1-855-452-5696
China (Landline):	800-870-0205
China (Mobile):	400-120-0932
Hong Kong:	800-963-117
United Kingdom:	0-808-234-0072
International:	+61-2-8199-0299
Conference ID:	35582613

A live webcast of the conference call and replay will be available on the investor relations page of WuXi PharmaTech’s website at http://www.wuxiapptec.com.

About WuXi PharmaTech

WuXi PharmaTech is a leading pharmaceutical, biotechnology, and medical device R&D outsourcing company, with operations in China and the United States. As a research-driven and customer-focused company, WuXi PharmaTech provides a broad and integrated portfolio of laboratory and manufacturing services throughout the drug and medical device R&D process. WuXi PharmaTech’s services are designed to assist its global partners in shortening the cycle and lowering the cost of drug and medical device R&D. WuXi PharmaTech’s operating subsidiaries are known as WuXi AppTec. For more information, please visit: http://www.wuxiapptec.com.

9

Forward-Looking Statements

This press release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements are not historical facts, but instead are predictions about future events. Examples of forward-looking statements in this press release include statements about our second-quarter and full-year 2013 guidance and our goal of building an open-access technology platform. Although we believe that our predictions are reasonable, future events are inherently uncertain and our forward-looking statements may turn out to be incorrect. Our forward-looking statements are subject to risks relating to, among other things, our ability to control our costs and sustain revenue growth, to realize the anticipated benefits of our investments, to protect our clients’ intellectual property and to compete effectively. Additional information about these and other relevant risks can be found in our Annual Report on Form 20-F for the year ended December 31, 2012. The forward-looking statements in this press release speak only on the date that they are made, and we assume no obligation to update any forward-looking statements except as required by law.

Use of Non-GAAP and Pro-Forma Financial Measures

We have provided the first-quarter 2012 and 2013 gross profit, gross margin, operating income, operating margin, net income, net margin, and earnings per ADS on a non-GAAP basis, which excludes share-based compensation expenses, the amortization and deferred tax impact of acquired intangible assets. We believe both management and investors benefit from referring to these non-GAAP financial measures in assessing our financial performance and liquidity and when planning and forecasting future periods. These non-GAAP operating measures are useful for understanding and assessing underlying business performance and operating trends. We expect to continue to provide net income and earnings per ADS on a non-GAAP basis using a consistent method on a quarterly basis. You should not view non-GAAP results on a stand-alone basis or as a substitute for results under GAAP, or as being comparable to results reported or forecasted by other companies, and should refer to the reconciliation of GAAP measures to non-GAAP measures for the indicated periods attached hereto.

Statement Regarding Unaudited Financial Information

The financial information set forth above is unaudited and subject to adjustments. Adjustments to the financial statements may be identified when our annual financial statements are prepared and audit work is performed for the yearend audit, which could result in significant differences from this unaudited financial information.

For more information, please contact:

WuXi PharmaTech (Cayman) Inc.

Ronald Aldridge (for investors)

Director of Investor Relations

Tel: +1-201-585-2048

Email: ir@wuxiapptec.com

Aaron Shi (for the media)

WuXi PharmaTech (Cayman) Inc.

Tel: +86-21-5046-4362

Email: pr@wuxiapptec.com

10