As filed with the Securities and Exchange Commission on January XX, 2013

File Nos. 2-91312, 811-04033

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. 54	¨

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 55	¨

SIT MUTUAL FUNDS II, INC.

(Exact Name of Registrant as Specified in Charter)

3300 IDS Center, Minneapolis, Minnesota 55402

(Address of Principal Executive Offices) (Zip Code)

(612) 332-3223

(Registrants’ Telephone Number, including Area Code)

Kelly K. Boston, Esq.

Sit Mutual Funds

3300 IDS Center

Minneapolis, Minnesota 55402

(Name and Address of Agent for Service)

Copy to:

Michael J. Radmer, Esq.

Dorsey & Whitney, LLP

50 South 6^th Street, Suite 1500

Minneapolis, Minnesota 55402

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

x immediately upon filing pursuant to paragraph (b) of rule 485

¨ on (specify date) pursuant to paragraph (b) of rule 485

¨ 60 days after filing pursuant to paragraph (a)(1) of rule 485

¨ on (specify date) pursuant to paragraph (a)(1) of rule 485

¨ 75 days after filing pursuant to paragraph (a)(2) of rule 485

¨ on (specify 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 and the Investment Company Act of 1940, the Registrant has duly caused this Registration Statement on Form N-1A to be signed on its behalf by the undersigned, thereunder duly authorized, in the City of Minneapolis, State of Minnesota, on the XX day of January 2013.

SIT MUTUAL FUNDS II, INC.
(Registrant)
By	/s/ Roger J. Sit
	Roger J. Sit, Chairman

Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to the Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the dates indicated. The enclosed Amendment does not contain disclosures that would render it ineligible to become effective pursuant to Rule 485(b).

Signature and Title
/s/ Roger J. Sit	Dated: January XX, 2013
Roger J. Sit, Chairman
(Principal Executive Officer)
/s/ Paul E. Rasmussen	Dated: January XX, 2013
Paul E. Rasmussen, Treasurer
(Principal Financial Officer and Accounting Officer)
William E. Frenzel, Director*
Edward M. Giles, Director*
Sidney L. Jones, Director*
Bruce C. Lueck, Director*
Donald W. Phillips, Director*
Barry N. Winslow, Director*
By /s/ Roger J. Sit	Dated: January XX, 2013
Roger J. Sit, Attorney-in-fact
*Pursuant to a power of attorney filed previously   with the Commission.

EXHIBIT INDEX

Index No.	Description of Exhibit
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-1-1.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