As filed with the Securities and Exchange Commission on May 20, 2020

Registration Nos.: 2-86966

811-3870

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	☒
Pre-Effective Amendment No.	☐
Post-Effective Amendment No. 72	☒
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	☒
Amendment No. 74	☒

Morgan Stanley U.S. Government Securities Trust

(Exact Name of Registrant as Specified in Charter)

522 Fifth Avenue New York, New York 10036

(Address of Principal Executive Office)

Registrant’s Telephone Number, Including Area Code:

(800) 548-7786

Mary E. Mullin, Esq.
1633 Broadway New York, New York 10019

(Name and Address of Agent for Service)

Copy to:

Carl Frischling, Esq.	Stuart M. Strauss, Esq.
Perkins Coie LLP	Dechert LLP
1155 Avenue of the Americas	1095 Avenue of the Americas
22nd Floor	New York, New York 10036
New York, New York 10036

Approximate Date of Proposed Public Offering:

As soon as practicable after this Post-Effective Amendment becomes effective.

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

☒	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.

Amending the Prospectus and Updating Financial Statements

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 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment to the 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 20^thday of May, 2020.

MORGAN STANLEY U.S. GOVERNMENT SECURITIES TRUST
By:	/s/  John H. Gernon
	John H. Gernon
	President and Principal Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment No. 72 has been signed below by the following persons in the capacities and on the dates indicated.

Signatures				Title	Date
(1)  Principal Executive Officer				President and Principal Executive Officer
By:		/s/ John H. Gernon			May 20, 2020
		John H. Gernon
(2)  Principal Financial Officer				Principal Financial Officer
By:		/s/ Francis J. Smith			May 20, 2020
		Francis J. Smith
(3)  Majority of the Trustees
Independent Trustees
	Frank L. Bowman		Joseph J. Kearns
	Kathleen A. Dennis		Michael F. Klein
	Nancy C. Everett		Patricia Maleski
	Jakki L. Haussler		Michael E. Nugent (Chairman)
	Dr. Manuel H. Johnson		W. Allen Reed
By:		/s/ Carl Frischling			May 20, 2020
		Carl Frischling
		Attorney-in-Fact for the Independent Trustees

EXHIBIT INDEX

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