UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

(Rule 13d-102)

Information Statement Pursuant to Rules 13d-1 and 13d-2

Under the Securities Exchange Act of 1934

WuXi PharmaTech (Cayman) Inc.

(Name of Issuer)

Ordinary Shares, par value U.S.$0.02 per share (represented by

American Depository Shares, each representing eight Ordinary Shares).

(Title of Class of Securities)

929352102

(CUSIP Number)

December 31, 2012

Date of Event Which Requires Filing of the Statement

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

x Rule 13d-1(b)

¨ Rule 13d-1(c)

¨ Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

1.	NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Commonwealth Bank of Australia
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Australian Capital Territory, Commonwealth of Australia
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 0
		6.	SHARED VOTING POWER 34,296,360 shares*
		7.	SOLE DISPOSITIVE POWER 0
		8.	SHARED DISPOSITIVE POWER 34,296,360 shares*
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 34,296,360 shares
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES    ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) Approximately 6.125% (based on 559,916,954 shares issued and outstanding as of September 30, 2012, per Form 6-K dated November 14, 2012)
12.	TYPE OF REPORTING PERSON BK/HC

* Held in the form of 4,287,045 American depository shares, each representing eight ordinary shares.

CUSIP NO. 929352102 13G Page 3 of 14

1.	NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Colonial Holding Company Limited
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION New South Wales, Commonwealth of Australia
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 0
		6.	SHARED VOTING POWER 34,296,360 shares*
		7.	SOLE DISPOSITIVE POWER 0
		8.	SHARED DISPOSITIVE POWER 34,296,360 shares*
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 34,296,360 shares*
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES    ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) Approximately 6.125% (based on 559,916,954 shares issued and outstanding as of September 30, 2012, per Form 6-K dated November 14, 2012)
12.	TYPE OF REPORTING PERSON HC

* Held in the form of 4,287,045 American depository shares, each representing eight ordinary shares.

CUSIP NO. 929352102 13G Page 4 of 14

1.	NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Commonwealth Insurance Holdings Limited
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION New South Wales, Commonwealth of Australia
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 0
		6.	SHARED VOTING POWER 34,296,360 shares*
		7.	SOLE DISPOSITIVE POWER 0
		8.	SHARED DISPOSITIVE POWER 34,296,360 shares*
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 34,296,360 shares*
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES    ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) Approximately 6.125% (based on 559,916,954 shares issued and outstanding as of September 30, 2012, per Form 6-K dated November 14, 2012)
12.	TYPE OF REPORTING PERSON HC

* Held in the form of 4,287,045 American depository shares, each representing eight ordinary shares.

CUSIP NO. 929352102 13G Page 5 of 14

1.	NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON Colonial First State Group Limited
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Victoria, Commonwealth of Australia
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 0
		6.	SHARED VOTING POWER 34,296,360 shares*
		7.	SOLE DISPOSITIVE POWER 0
		8.	SHARED DISPOSITIVE POWER 34,296,360 shares*
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 34,296,360 shares*
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES    ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) Approximately 6.125% (based on 559,916,954 shares issued and outstanding as of September 30, 2012, per Form 6-K dated November 14, 2012)
12.	TYPE OF REPORTING PERSON HC

* Held in the form of 4,287,045 American depository shares, each representing eight ordinary shares.

CUSIP NO. 929352102 13G Page 6 of 14

1.	NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON First State Investment Management (UK) Limited
2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a)  ¨        (b)  x
3.	SEC USE ONLY
4.	CITIZENSHIP OR PLACE OF ORGANIZATION Scotland, United Kingdom
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		5.	SOLE VOTING POWER 0
		6.	SHARED VOTING POWER 34,217,496 shares*
		7.	SOLE DISPOSITIVE POWER 0
		8.	SHARED DISPOSITIVE POWER 34,217,496 shares*
9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 34,217,496 shares*
10.	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES    ¨
11.	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) Approximately 6.11% (based on 559,916,954 shares issued and outstanding as of September 30, 2012, per Form 6-K dated November 14, 2012)
12.	TYPE OF REPORTING PERSON IA

* Held in the form of 4,277,187 American depository shares, each representing eight ordinary shares.

CUSIP NO. 929352102 13G Page 7 of 14

Item 1(a) Name of Issuer: WuXi PharmaTech (Cayman) Inc

Item 1(b) Address of Issuer’s Principal Executive Offices:

288 Fute Zhong Road

Waigaoqiao Free Trade Zone

Shanghai 200131

China

Item 2(a) Name of Person Filing

Item 2(b) Address of Principal Business Office

Item 2(c) Citizenship

Commonwealth Bank of Australia

Ground Floor, Tower 1

201 Sussex Street

Sydney, New South Wales, 2000

Commonwealth of Australia

Australian Capital Territory

Colonial Holding Company Limited

Ground Floor, Tower 1

201 Sussex Street

Sydney, New South Wales, 2000.

Commonwealth of Australia

New South Wales

Commonwealth Insurance Holdings Limited

Ground Floor, Tower 1

201 Sussex Street

Sydney, New South Wales, 2000

Commonwealth of Australia

New South Wales

Colonial First State Group Limited

Ground Floor, Tower 1

201 Sussex Street

Sydney, New South Wales, 2000

Commonwealth of Australia

Victoria

First State Investment Management (UK) Limited

23 St Andrew Square

Edinburgh EH2 1BB

Scotland

Item 2(d) Title of Class of Securities:

American Depositary Shares

Item 2(e) CUSIP Number: 929352102

CUSIP NO. 929352102 13G Page 8 of 14

Item 3 If this statement is filed pursuant to Rules 13d-1(b), or 13d-2(b) or (c), check whether the person filing is a:

(a) ¨     Broker or dealer registered under Section 15 of the Exchange Act;

(b) ¨     Bank as defined in Section 3(a)(6) of the Exchange Act;

(c) ¨     Insurance company as defined in Section 3(a)(19) of the Exchange Act;

(d) ¨     Investment company registered under Section 8 of the Investment Company Act;

(e) ¨     An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);

(f) ¨     An employee benefit plan or endowment fund in accordance with Rule 13d-1(b)(1)(ii)(F);

(g) x     A parent holding company or control person in accordance with Rule 13d-1(b)(1)(ii)(G);

(h) ¨     A savings association as defined in Section 3(b) of the Federal Deposit Insurance Act;

(i) ¨     A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the

Investment Company Act;

(j) x    A non-U.S. institution in accordance with §240.13d–1(b)(1)(ii)(J);

(k) ¨     Group, in accordance with Rule 13d-1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with §240.13d–1(b)(1)(ii)(J), please specify the type of institution: First State Investment Management (UK) Limited is an investment adviser registered pursuant to the law of the jurisdiction in which it is located.

If this statement is filed pursuant to Rule 13d-1(c), check this box:    ¨

Item 4 Ownership:

(a) Amount beneficially owned:

Incorporated by reference to Item 9 of the cover page pertaining to each reporting person.

(b) Percent of Class:

Incorporated by reference to Item 11 of the cover page pertaining to each reporting person.

(c) Number of shares as to which such person has:

(i) sole power to vote or to direct the vote:

Incorporated by reference to Item 5 of the cover page pertaining to each reporting person.

(ii) shared power to vote or to direct the vote:

Incorporated by reference to Item 6 of the cover page pertaining to each reporting person.

CUSIP NO. 929352102 13G Page 9 of 14

(iii) sole power to dispose or to direct the disposition of:

Incorporated by reference to Item 7 of the cover page pertaining to each reporting person.

(iv) shared power to dispose or to direct the disposition of:

Incorporated by reference to Item 8 of the cover page pertaining to each reporting person.

Item 5 Ownership of Five Percent or Less of a Class:

Not Applicable.

Item 6 Ownership of More than Five Percent on Behalf of Another Person:

Not Applicable.

Item 7 Identification and Classification of the Subsidiary which Acquired the Security Being Reported on by the Parent Holding Company:

See Exhibit 99.2.

Item 8 Identification and Classification of Members of the Group:

Not Applicable.

Item 9 Notice of Dissolution of Group:

Not Applicable.

Item 10 Certification:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction

CUSIP NO. 929352102 13G Page 10 of 14

having that purpose or effect. I also certify that, to the best of my knowledge and belief, the foreign regulatory schemes applicable to the relevant subsidiaries referenced in Exhibit 99.2 to this Schedule 13G are substantially comparable to the regulatory scheme applicable to the functionally equivalent U.S. institution(s), and that I undertake to furnish to the Commission staff, upon request, information that would otherwise be disclosed in a Schedule 13D.

After reasonable inquiry and to the best of its knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Dated this 14 day of February, 2013.

CUSIP NO. 929352102 13G Page 11 of 14

Commonwealth Bank of Australia
By:	/s/ John Damien Hatton
Name:   John Damien Hatton
Title:     Company Secretary
Colonial Holding Company Limited
By:	/s/ John Damien Hatton
Name:   John Damien Hatton
Title:     Director
Commonwealth Insurance Holdings Limited
By:	/s/ John Damien Hatton
Name:   John Damien Hatton
Title:     Director
Colonial First State Group Limited
By:	/s/ John Damien Hatton
Name:   John Damien Hatton
Title:     Director
First State Investment Management (UK) Limited
By:	/s/ Gary Withers
Name:   Gary Withers
Title:     Director

CUSIP NO. 929352102 13G Page 12 of 14

INDEX TO EXHIBITS

Exhibit No.	Exhibit
99.1	Joint Filing Agreement
99.2	Item 7 Information