UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 4)1

Avigen, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

053690103

(CUSIP Number)

Elizabeth Delaney

BVF Partners L.P.

900 North Michigan Avenue

Suite 1100

Chicago, Illinois 60611

(312) 506-6500

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

December 24, 2008

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box x.

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See § 240.13d-7 for other parties to whom copies are to be sent.

_______________

1              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).

CUSIP NO. 053690103

1	NAME OF REPORTING PERSON Biotechnology Value Fund, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 1,975,340
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 1,975,340
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,975,340
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 6.64%
14	TYPE OF REPORTING PERSON PN

2

CUSIP NO. 053690103

1	NAME OF REPORTING PERSON Biotechnology Value Fund II, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 1,364,911
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 1,364,911
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,364,911
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.58%
14	TYPE OF REPORTING PERSON PN

3

CUSIP NO. 053690103

1	NAME OF REPORTING PERSON BVF Investments, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 4,969,764
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 4,969,764
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 4,969,764
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 16.69%
14	TYPE OF REPORTING PERSON OO

4

CUSIP NO. 053690103

1	NAME OF REPORTING PERSON Investment 10, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Illinois
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 509,585
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 509,585
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 509,585
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.71%
14	TYPE OF REPORTING PERSON OO

5

CUSIP NO. 053690103

1	NAME OF REPORTING PERSON BVF Partners L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 8,819,600
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 8,819,600
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 8,819,600
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 29.63%
14	TYPE OF REPORTING PERSON PN, HC

6

CUSIP NO. 053690103

1	NAME OF REPORTING PERSON BVF Inc.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) x   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 0
	8	SHARED VOTING POWER 8,819,600
	9	SOLE DISPOSITIVE POWER 0
	10	SHARED DISPOSITIVE POWER 8,819,600
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 8,819,600
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 29.63%
14	TYPE OF REPORTING PERSON CO, HC

7

CUSIP NO. 053690103

The following constitutes Amendment No. 4 to the Schedule 13D filed by the undersigned ("Amendment No. 4").  This Amendment No. 4 amends the Schedule 13D as specifically set forth.

ITEM 4. Purpose of Transaction

Item 4 is hereby amended to add the following:

On December 22, 2008 MediciNova, Inc. (“MediciNova”) described details of a Proposed Merger between MediciNova and Avigen, Inc. ("Avigen") in a letter to Avigen's Chairman, Zola Horovitz. The Reporting Persons hereby express their full and enthusiastic support for this Proposed Merger and believe it is the best interest of all Avigen shareholders.  The Reporting Persons presently have no economic interest in MediciNova. The Reporting Persons call on Avigen's Board of Directors to negotiate with MediciNova and work to consummate the Proposed Merger expeditiously.

The Reporting Persons support the Proposed Merger for the following reasons:

1.  Downside Protection:  The Proposed Merger provides for the same downside protection that the Reporting Persons encouraged Avigen to implement directly (which Avigen rejected). Subsequent to the Proposed Merger, if MediciNova is unsuccessful, Avigen shareholders will receive approximately the current liquidation value of Avigen (which the Reporting Persons estimate to be approximately $1.20/share, net of debt and expenses), as determined by an independent auditor. Incredibly, in a worst case scenario, the Proposed Merger would yield about a 60% premium to Avigen's current stock price.

2.  Extraordinary Upside Potential:  If MediciNova is successful post-merger, Avigen shareholders could own a substantial percentage of MediciNova (which the Reporting Persons estimate to be approximately 45% of the combined company).  Thus, in a best case scenario, Avigen shareholders could enjoy an extraordinary, uncapped return. For this reason, the Proposed Merger is superior to an immediate liquidation of Avigen.

3. Free Option:  Shareholders have at least one year after the merger is consummated to choose downside protection or upside potential, as described above. This decision can be based on information obtained over the course of the free option period, including the stock performance of MediciNova.  This free option period offers shareholders tremendous upside potential with virtually no risk.

4.  Change of Control:  The Proposed Merger would result in new stewardship of Avigen's assets, curtailing current management's stated plan of seeking ways to utilize (and we fear waste) Avigen's cash in any way they wish. This is a particularly frightening prospect in light of CEO Ken Chahine's recent statements that "it’s hard to put a finger on exactly what we would do", that he "intends to build" and that he "thinks that there are opportunities outside of therapeutics."

5.  Unique Synergies:  The Reporting Persons believe there are unique synergies between MediciNova and Avigen which likely would not exist with other potential acquirers of Avigen.  These synergies give rise to the compelling nature of the Proposed Merger.

BVF wishes to see the Proposed Merger brought to a shareholder vote as soon as practical and urges other Avigen shareholders to support this offer.

8

CUSIP NO. 053690103

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:  December 29, 2008
	BIOTECHNOLOGY VALUE FUND, L.P.*
	By:	BVF Partners L.P., its general partner
		By:	BVF Inc., its general partner
			By:	/s/ Mark N. Lampert
				Mark N. Lampert
				President
	BIOTECHNOLOGY VALUE FUND II, L.P.*
	By:	BVF Partners L.P., its general partner
		By:	BVF Inc., its general partner
			By:	/s/ Mark N. Lampert
				Mark N. Lampert
				President
	BVF INVESTMENTS, L.L.C.*
	By:	BVF Partners L.P., its manager
		By:	BVF Inc., its general partner
			By:	/s/ Mark N. Lampert
				Mark N. Lampert President
	INVESTMENT 10, L.L.C.*
	By:	BVF Partners L.P., its investment manager
		By:	BVF Inc., its general partner
			By:	/s/ Mark N. Lampert
				Mark N. Lampert
				President
	BVF PARTNERS L.P. *
	By:	BVF Inc., its general partner
		By:	/s/ Mark N. Lampert
			Mark N. Lampert
			President
	BVF INC.*
	By:	/s/ Mark N. Lampert
		Mark N. Lampert
		President

*The Reporting Person disclaims beneficial ownership except to the extent of its pecuniary interest therein.

9