As filed with the Securities and Exchange Commission on November 28, 2018

Securities Act of 1933 Registration No. 2-80543

Investment Company Act of 1940 Registration No. 811-03605

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. 94	☒

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940

Amendment No. 116 ☒

(Check appropriate box or boxes)

NORTHERN INSTITUTIONAL FUNDS

(Exact Name of Registrant as Specified in Charter)

50 South LaSalle Street

Chicago, Illinois 60603

(Address of Principal Executive Offices)

800-637-1380

(Registrant’s Telephone Number, including Area Code)

Name and Address of Agent for Service:   Diana E. McCarthy Drinker Biddle & Reath LLP One Logan Square, Suite 2000 Philadelphia, Pennsylvania 19103-6996 with a copy to:   Kevin P. O’Rourke Jose J. Del Real, Esq. The Northern Trust Company 50 South LaSalle Street Chicago, Illinois 60603

It Is Proposed That This Filing 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)

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 (the “Securities Act”), and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Post-Effective Amendment No. 94 to its Registration Statement under Rule 485(b) under the Securities Act and has duly caused this Post-Effective Amendment No. 94 to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Chicago and State of Illinois on the 28^th day of November, 2018.

NORTHERN INSTITUTIONAL FUNDS
By:	/s/ Peter K. Ewing
	Peter K. Ewing
	President

Pursuant to the requirements of the Securities Act, this Post-Effective Amendment No. 94 to Registrant’s Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

Name	Title	Date
/s/ Peter K. Ewing	President (Principal Executive Officer)	November 28, 2018
Peter K. Ewing
/s/ Randal E. Rein	Treasurer (Principal Financial Officer and	November 28, 2018
Randal E. Rein	Principal Accounting Officer)
* William L. Bax	Trustee	November 28, 2018
William L. Bax
* Mark G. Doll	Trustee	November 28, 2018
Mark G. Doll
* Sandra Polk Guthman	Trustee	November 28, 2018
Sandra Polk Guthman
* Thomas A. Kloet	Trustee	November 28, 2018
Thomas A. Kloet
* David R. Martin	Trustee	November 28, 2018
David R. Martin
* Cynthia R. Plouché	Trustee	November 28, 2018
Cynthia R. Plouché
* Mary Jacobs Skinner	Trustee	November 28, 2018
Mary Jacobs Skinner
* Casey J. Sylla	Trustee	November 28, 2018
Casey J. Sylla
* Shundrawn A. Thomas	Trustee	November 28, 2018
Shundrawn A. Thomas
/s/ Peter K. Ewing
* By Peter K. Ewing    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
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase