As filed with the U.S. Securities and Exchange Commission on December 24, 2013

Securities Act File No. 333-179904

Investment Company Act File No. 811-22649

UNITED STATES

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. 41	x
and/or
REGISTRATION STATEMENT
UNDER
THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 41	x

(Check appropriate box or boxes)

iShares U.S. ETF Trust

(Exact Name of Registrant as Specified in Charter)

c/o State Street Bank and Trust Company

200 Clarendon Street

Boston, MA 02116

(Address of Principal Executive Office)(Zip Code)

Registrant’s Telephone Number, including Area Code (415) 670-2000

The Corporation Trust Company

1209 Orange Street

Wilmington, DE 19801

(Name and Address of Agent for Service)

With Copies to:

MARGERY K. NEALE, ESQ. WILLKIE FARR & GALLAGHER LLP 787 SEVENTH AVENUE NEW YORK, NY 10019-6099 BENJAMIN J. HASKIN, ESQ. WILLKIE FARR & GALLAGHER LLP 1875 K STREET, N.W. WASHINGTON, D.C. 20006-1238 EDWARD BAER, ESQ. BLACKROCK FUND ADVISORS 400 HOWARD STREET SAN FRANCISCO, CA 94105

Continuous

(December 24, 2013)

It is proposed that this filing will become effective:

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)

If appropriate, check the following box:

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

This filing relates solely to the following Fund, a series of iShares U.S. ETF Trust:

iShares Liquidity Income ETF

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all the requirements for the effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933, as amended, and has duly caused this Post-Effective Amendment No. 41 to the Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of San Francisco and the State of California on the 23^rd day of December, 2013.

iSHARES U.S. ETF TRUST

By:
	Michael Latham*
	President and Trustee
	Date: December 23, 2013

Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No. 41 to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

Michael Latham*

President and Trustee

Date: December 23, 2013

John E. Martinez*

Trustee

Date: December 23, 2013

George G.C. Parker*

Trustee

Date: December 23, 2013

Cecilia H. Herbert*

Trustee

Date: December 23, 2013

Charles A. Hurty*

Trustee

Date: December 23, 2013

John E. Kerrigan*

Trustee

Date: December 23, 2013

Robert H. Silver*

Trustee

Date: December 23, 2013

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Robert S. Kapito*

Trustee

Date: December 23, 2013

Madhav V. Rajan*

Trustee

Date: December 23, 2013

/s/ Jack Gee

Jack Gee

Treasurer

Date: December 23, 2013

/s/ Jack Gee

* By: Jack Gee

Attorney-in-fact

Date: December 23, 2013

* Powers of Attorney, each dated June 11, 2013, for Michael Latham, Charles A. Hurty, Cecilia H. Herbert, John E. Kerrigan, Robert H. Silver, George G.C. Parker, John E. Martinez, Madhav V. Rajan and Robert S. Kapito are incorporated herein by reference to Post-Effective Amendment No. 17, filed August 22, 2013.

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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

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