Registration No. 33-08054

File No. 811-4803

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No. _____	o
Post-Effective Amendment No. 37	x

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 38	x

Oppenheimer Municipal Fund

_____________________________________________________________

(Exact Name of Registrant as Specified in Charter)

6803 South Tucson Way, Centennial, Colorado 80112

_____________________________________________________________

(Address of Principal Executive Offices)    (Zip Code)

(303) 768-3200

_____________________________________________________________

(Registrant’s Telephone Number, including Area Code)

Arthur S. Gabinet, Esq.

OppenheimerFunds, Inc.

2 World Financial Center, New York, New York 10281-1008

_____________________________________________________________

(Name and Address of Agent for Service)

It is proposed that this filing will become effective (check appropriate box):

x Immediately upon filing pursuant to paragraph (b)

o On ____________ pursuant to paragraph (b)

o 60 days after filing pursuant to paragraph (a)(1)

o On pursuant to paragraph (a)(1)

o 75 days after filing pursuant to paragraph (a)(2)

o On _______________ pursuant to paragraph (a)(2) of Rule 485

If appropriate, check the following box:

o This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York and State of New York on the 17^th day of February 2011.

OPPENHEIMER MUNICIPAL FUND
By:	William F. Glavin, Jr.*
	William F. Glavin, Jr., President Principal Executive Officer and Trustee

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities on the dates indicated:

Signatures	Title	Date
Brian F. Wruble*	Chairman of the Board of Trustees	February 17, 2011
Brian F. Wruble
William F. Glavin, Jr.*	President, Principal Executive Officer and Trustee	February 17, 2011
William F. Glavin, Jr.
Brian W. Wixted*	Treasurer, Principal Financial & Accounting Officer	February 17, 2011
Brian W. Wixted
David K. Downes*	Trustee	February 17, 2011
David K. Downes
Matthew P. Fink*	Trustee	February 17, 2011
Matthew P. Fink
Phillip A. Griffiths*	Trustee	February 17, 2011
Phillip A. Griffiths
Mary F. Miller*	Trustee	February 17, 2011
Mary F. Miller
Joel W. Motley*	Trustee	February 17, 2011
Joel W. Motley
Mary Ann Tynan*	Trustee	February 17, 2011
Mary Ann Tynan
Joseph M. Wikler*	Trustee	February 17, 2011
Joseph M. Wikler
Peter I. Wold*	Trustee	February 17, 2011
Peter I. Wold

*By:	/s/ Mitchell J. Lindauer
	Mitchell J. Lindauer, Attorney-in-Fact

EXHIBIT INDEX

Exhibit No.	Description
Ex-101.INS	XBRL Instance Document
Ex-101.SCH	XBRL Taxonomy Extension Schema Document
Ex-101.CAL	XBRL Taxonomy Extension Calculation Linkbase Document
Ex-101.DEF	XBRL Taxonomy Extension Definition Linkbase
Ex-101.LAB	XBRL Taxonomy Extension Labels Linkbase
Ex-101.PRE	XBRL Taxonomy Extension Presentation Linkbase Document

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