SC 13G

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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. )*

XENOPORT, INC.

(Name of Issuer)

COMMON STOCK

(Title of Class of Securities)

98411C100

(CUSIP Number)

December 31, 2005

(Date of Event Which Requires Filing of this Statement)

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

     o Rule 13d-1(b)

     o Rule 13d-1(c)

     þ 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 the disclosures provided in a prior cover page.

The information required in 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).

Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

CUSIP No. 98411C100  13G Page 2  of  8 

1	NAMES OF REPORTING PERSONS: Venrock Associates
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
	13-6300995
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ1
	(b)   o
3	SEC USE ONLY:
4	CITIZENSHIP OR PLACE OF ORGANIZATION:
	New York, United States
		5	SOLE VOTING POWER:
NUMBER OF			0
SHARES		6	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			1,447,1402
EACH		7	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			0
WITH:		8	SHARED DISPOSITIVE POWER:
			1,477,1402
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	1,447,1402
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
	7.3%
12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	PN

¹ Venrock Associates, Venrock Associates II, L.P. and Venrock Entrepreneurs Fund, L.P. are members of a group for purposes of this Schedule 13G.

² Consists of 581,574 shares of common stock owned by Venrock Associates, 836,900 shares of common stock owned by Venrock Associates II, L.P. and 28,666 shares of common stock owned by Venrock Entrepreneurs Fund, L.P.

CUSIP No. 98411C100  13G Page 3  of  8 

1	NAMES OF REPORTING PERSONS: Venrock Associates II, L.P.
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
	13-3844754
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ1
	(b)   o
3	SEC USE ONLY:
4	CITIZENSHIP OR PLACE OF ORGANIZATION:
	New York, United States
		5	SOLE VOTING POWER:
NUMBER OF			0
SHARES		6	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			1,447,1402
EACH		7	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			0
WITH:		8	SHARED DISPOSITIVE POWER:
			1,447,1402
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	1,447,1402
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
	7.3%
12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	PN

¹ Venrock Associates, Venrock Associates II, L.P. and Venrock Entrepreneurs Fund, L.P. are members of a group for purposes of this Schedule 13G.

² Consists of 581,574 shares of common stock owned by Venrock Associates, 836,900 shares of common stock owned by Venrock Associates II, L.P. and 28,666 shares of common stock owned by Venrock Entrepreneurs Fund, L.P.

CUSIP No. 98411C100  13G Page 4  of  8 

1	NAMES OF REPORTING PERSONS: Venrock Entrepreneurs Fund, L.P.
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY):
	13-4078492
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
	(a)   þ1
	(b)   o
3	SEC USE ONLY:
4	CITIZENSHIP OR PLACE OF ORGANIZATION:
	New York, United States
		5	SOLE VOTING POWER:
NUMBER OF			0
SHARES		6	SHARED VOTING POWER:
BENEFICIALLY
OWNED BY			1,447,1402
EACH		7	SOLE DISPOSITIVE POWER:
REPORTING
PERSON			0
WITH:		8	SHARED DISPOSITIVE POWER:
			1,447,1402
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
	1,447,1402
10	CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
	o
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
	7.3%
12	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
	PN

¹ Venrock Associates, Venrock Associates II, L.P. and Venrock Entrepreneurs Fund, L.P. are members of a group for purposes of this Schedule 13G.

² Consists of 581,574 shares of common stock owned by Venrock Associates, 836,900 shares of common stock owned by Venrock Associates II, L.P. and 28,666 shares of common stock owned by Venrock Entrepreneurs Fund, L.P.

CUSIP No. 98411C100  13G Page 5  of  8 

     Introductory Note: This Statement on Schedule 13G is filed on behalf of Venrock Associates, a limited partnership organized under the laws of the State of New York (“Venrock”), Venrock Associates II, L.P., a limited partnership organized under the laws of the State of New York (“Venrock II”) and Venrock Entrepreneurs Fund, L.P., a limited partnership organized under the laws of the State of New York (“Entrepreneurs Fund” and collectively with Venrock and Venrock II, the “Venrock Entities”) in respect of shares of common stock of XenoPort, Inc.

Item 1(a)	Name of Issuer:
	XenoPort, Inc.
Item 1(b)	Address of Issuer’s Principal Executive Offices:
	3410 Central Expressway
	Santa Clara, CA 95051
Item 2(a)	Name of Person Filing:
	Venrock Associates
	Venrock Associates II, L.P.
	Venrock Entrepreneurs Fund, L.P.

Item 2(b)	Address of Principal Business Office or, if none, Residence:
New York Office:		Menlo Park Office:	Cambridge Office:
30 Rockefeller Plaza		2494 Sand Hill Road	55 Cambridge Parkway
Suite 5508		Suite 200	Suite 100
New York, NY 10112		Menlo Park, CA 94025	Cambridge, MA 02142

Item 2(c)	Citizenship:
	Each of Venrock, Venrock II and Entrepreneurs Fund are limited partnerships organized in the State of New York.
Item 2(d)	Title of Class of Securities:
	Common Stock
Item 2(e)	CUSIP Number
	98411C100
Item 3	Not applicable.

CUSIP No. 98411C100  13G Page 6  of  8 

Item 4	Ownership
	(a) and (b)

     Venrock beneficially owns 581,574 shares of common stock, or 2.9% or the outstanding shares of common stock. Venrock II owns 836,900 shares of common stock, or 4.2% or the outstanding shares of common stock. Entrepreneurs Fund owns 28,666 shares of common stock, or 0.1% or the outstanding shares of common stock.

     (c)

     Each of the Venrock Entities has sole power to vote or to direct the vote of no shares of the common stock, sole power to dispose or to direct the disposition of no shares of the common stock, shared power to vote or to direct the vote of 1,447,140 shares of the common stock and shared power to dispose or to direct the disposition of 1,447,140 shares of the common stock.

Item 5	Ownership of Five Percent or Less of a Class: If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following.o
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:
	Not applicable.
Item 8	Identification and Classification of Members of the Group:
	This Schedule is being filed pursuant to Rule 13d-1(d). The identities of
	each of the Venrock Entities are stated in Item 2(a).
Item 9	Notice of Dissolution of Group:
	Not applicable.

CUSIP No. 98411C100  13G Page 7  of  8 

Item 10	Certification
	Not applicable.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this Statement is true, complete and correct.

Dated: February 14, 2006	VENROCK ASSOCIATES
	By:	/s/ Anthony B. Evnin
	Name:	Anthony B. Evnin
	Title:	Managing General Partner
Dated: February 14, 2006	VENROCK ASSOCIATES II, L.P.
	By:	/s/ Anthony B. Evnin
	Name:	Anthony B. Evnin
	Title:	Managing General Partner
Dated: February 14, 2006	VENROCK ENTREPRENEURS FUND, L.P.
	By:	/s/ Anthony B. Evnin
	Name:	Anthony B. Evnin
	Title:	Managing General Partner

CUSIP No. 98411C100  13G Page 8  of  8 

EXHIBIT INDEX

Exhibit No.
99.1	Agreement pursuant to 13d-1(k)(1) among Venrock Associates, Venrock Associates II, L.P. and Venrock Entrepreneurs Fund, L.P.

EX-99.1

Exhibit 99.1

AGREEMENT

     Pursuant to Rule 13d-1(k)(1) promulgated pursuant to the Securities Exchange Act of 1934, as amended, the undersigned agree that the attached Schedule 13G is being filed on behalf of each of the undersigned.

Dated: February 14, 2006	VENROCK ASSOCIATES
	By:	/s/ Anthony B. Evnin
	Name:	Anthony B. Evnin
	Title:	Managing General Partner
Dated: February 14, 2006	VENROCK ASSOCIATES II, L.P.
	By:	/s/ Anthony B. Evnin
	Name:	Anthony B. Evnin
	Title:	Managing General Partner
Dated: February 14, 2006	VENROCK ENTREPRENEURS FUND, L.P.
	By:	/s/ Anthony B. Evnin
	Name:	Anthony B. Evnin
	Title:	Managing General Partner