As filed with the U.S. Securities and Exchange Commission on December 30, 2013

                          File Nos. 333-179904 and 811-22649

 UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	x
Post-Effective Amendment No. 43	x
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	x
Amendment No. 43	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.	BENJAMIN J. HASKIN, ESQ.	EDWARD BAER, ESQ.
WILLKIE FARR & GALLAGHER LLP	WILLKIE FARR & GALLAGHER LLP	BLACKROCK FUND ADVISORS
787 SEVENTH AVENUE	1875 K STREET, N.W.	400 HOWARD STREET
NEW YORK, NY 10019-6099	WASHINGTON, D.C. 20006-1238	SAN FRANCISCO, CA 94105

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

¨     Immediately upon filing pursuant to paragraph (b)	x    On January 29, 2014, 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:

x The post-effective amendment designates a new effective date for a previously filed post-effective amendment.

Explanatory Note

This Post-Effective Amendment No. 43 to the Registrant’s Registration Statement on Form N-1A is being filed pursuant to paragraph (b)(1)(iii) of Rule 485 of the Securities Act of 1933, as amended (the “1933 Act”), solely for the purpose of delaying, until January 29, 2014, the effectiveness of the registration statement for the iShares Enhanced International Small-Cap ETF (the “Fund”), filed in Post-Effective Amendment No. 23 on October 4, 2013, pursuant to paragraph (a) of Rule 485 of the 1933 Act.

The effectiveness of the Registration Statement of the Fund was previously delayed pursuant to paragraph (b)(1)(iii) of Rule 485 of the 1933 Act as follows:

PEA No.	Date Filed	Automatic Effective Date
31	December 2, 2013	January 2, 2014

This Post-Effective Amendment No. 43 incorporates by reference the information contained in Parts A, B and C of Post-Effective Amendment No. 23.

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)(1)(iii) of the Securities Act of 1933, as amended, and has duly caused this Post-Effective Amendment No. 43 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 30th day of December, 2013.

iSHARES U.S. ETF TRUST 

By:
	Michael Latham*
	President and Trustee
	Date: December 30, 2013

Pursuant to the requirements of the Securities Act of 1933, as amended, this Post-Effective Amendment No. 43 to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

By:
	Michael Latham*
	President and Trustee
	Date: December 30, 2013
	John E. Martinez*
	Trustee
	Date: December 30, 2013
	George G.C. Parker*
	Trustee
	Date: December 30, 2013
	Cecilia H. Herbert*
	Trustee
	Date: December 30, 2013
	Charles A. Hurty*
	Trustee
	Date: December 30, 2013

	John E. Kerrigan*
	Trustee
	Date: December 30, 2013
	Robert H. Silver*
	Trustee
	Date: December 30, 2013
	Robert S. Kapito*
	Trustee
	Date: December 30, 2013
	Madhav V. Rajan*
	Trustee
	Date: December 30, 2013
	/s/ Jack Gee
	Jack Gee
	Treasurer
	Date: December 30, 2013
* By:	/s/ Jack Gee
	Jack Gee
	Attorney-in-fact
	Date: December 30, 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.