As filed with the Securities and Exchange Commission on November 10, 2011

File Nos. 002-62436

811-02864

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER
THE SECURITIES ACT OF 1933	x
Pre-Effective Amendment No.	¨
Post-Effective Amendment No. 50	x
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 49	x

(Check appropriate box or boxes)

PIONEER BOND FUND

(Exact Name of Registrant as Specified in Charter)

60 State Street, Boston, Massachusetts 02109

(Address of Principal Executive Offices) (Zip Code)

Registrant’s Telephone Number, including Area Code: (617) 742-7825

Terrence J. Cullen, Pioneer Investment Management, Inc.,

Boston, Massachusetts 02109

(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)

¨ on [date] pursuant to paragraph (b)

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

¨ on [date] pursuant to paragraph (a)(1)

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

¨ on [date] pursuant to paragraph (a)(2)of Rule 485.

If appropriate, check the following box:

¨ 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, as amended, and the Investment Company Act of 1940, as amended, the Fund certifies that it meets all of the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) of the Securities Act of 1933. The fund has duly caused this Post-Effective Amendment No. 50 to its Registration Statement to

be signed on its behalf by the undersigned, duly authorized, in the City of Boston and The Commonwealth of Massachusetts on the 10th day of November, 2011.

PIONEER BOND FUND
By:	/s/ Daniel K. Kingsbury
	Daniel K. Kingsbury
	Executive Vice President

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities indicated below on November 10, 2011:

	Signature	Title
	John F. Cogan, Jr.* John F. Cogan, Jr.	Chairman of the Board, President (Principal Executive Officer) and Trustee
	Mark E. Bradley* Mark E. Bradley	Treasurer (Principal Financial and Accounting Officer)
	David R. Bock* David R. Bock	Trustee
	Mary K. Bush* Mary K. Bush	Trustee
	Benjamin M. Friedman* Benjamin M. Friedman	Trustee
	Margaret B. W. Graham* Margaret B. W. Graham	Trustee
	/s/ Daniel K. Kingsbury Daniel K. Kingsbury	Executive Vice President and Trustee
	Thomas J. Perna* Thomas J. Perna	Trustee
	Marguerite A. Piret* Marguerite A. Piret	Trustee
*By:	/s/ Daniel K. Kingsbury	Dated: November 10, 2011
	Daniel K. Kingsbury
	Attorney-in-fact

EXHIBIT INDEX

Index Number	Description of Index
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Document
EX-101.DEF	XBRL Taxonomy Extension Definition Document
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase