PAO Powershares Riverfront Tactical Balanced Growth Portfolio

AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 23, 2008.

No. 333-102228

No. 811-21265

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

(Check appropriate box or boxes)

POWERSHARES EXCHANGE-TRADED FUND TRUST

(Exact Name of Registrant as Specified in Charter)

301 West Roosevelt Road

Wheaton, IL 60187

(Address of Principal Executive Office)

Registrant’s Telephone Number, including Area Code:  (800) 983-0903

APPROXIMATE DATE OF PROPOSED PUBLIC OFFERING:

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

o                                     immediately upon filing pursuant to paragraph (b) of Rule 485.

x                                   on June 20, 2008 pursuant to paragraph (b) of Rule 485.

o                                     60 days after filing pursuant to paragraph (a)(1) of Rule 485.

o                                     on [date] pursuant to paragraph (a) of Rule 485.

o                                     75 days after filing pursuant to paragraph (a)(2) of Rule 485.

o                                     on [date] pursuant to paragraph (a) of Rule 485.

The sole purpose of this filing is to delay the effectiveness of the Trust’s  Post-Effective Amendment No. 159 to its Registration Statement until June 20, 2008. Post-Effective Amendment No. 159 to the Trust’s Registration Statement relates to the PowerShares Lux Nanotech Portfolio, which was created pursuant to Post-Effective Amendment No. 35 to the Trust’s Registration Statement filed on July 12, 2005.  Post-Effective Amendment No. 159 to the Trust’s Registration Statement was filed in order to include global securities in PowerShares Lux Nanotech Portfolio’s portfolio.  The effectiveness of the Registration Statement relating to this change was delayed pursuant to Post-Effective Amendment Nos. 175 and 180 to the Trust’s Registration Statement filed on March 31, 2008 and April 25, 2008, respectively. Parts A, B and C of Registrant’s Post-Effective Amendment No. 159 under the Securities Act of 1933 and Amendment No. 161 under the Investment  Company Act of 1940, filed on January 31, 2008 are incorporated by reference herein.

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SIGNATURES

Pursuant to the requirements of the Securities Act and the Investment Company Act, the Fund certifies that it meets all of the requirements for effectiveness of this registration statement under Rule 485(b) under the Securities Act and has duly caused this registration statement to be signed on its behalf by the undersigned, duly authorized, in the City of Wheaton and State of Illinois, on the 23rd day of May, 2008.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed below by the following persons in the capacities indicated on the dates indicated.

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