Pioneer Interest Shares (MUO) Declares Special Distribution.

BOSTON -- Pioneer Interest Shares (NYSE: MUO) today announced the declaration of a special dividend for October 2007. The closing market price, annualized yield and NAV yield are based on data as of September 28, 2007.

Ex Date: October 5, 2007

Record Date: October 10, 2007

Payable Date: October 17, 2007

Distribution  <          <  Market  <          <  Mark-

NAV

NAV
Per Share     <          <  Price   <          <  Yield

Price

Yield
              <          <          <          <




$0.0407       <          <  $11.98  <          <  5.90%

$12.11

5.84%

This special dividend is in anticipation of the proposed reorganization of the Fund, a closed-end fund, into Pioneer Bond Fund, an open-end fund, subject to shareholder approval at a special meeting to be held on October 16, 2007.

Pioneer Interest Shares is a closed-end investment company which trades on the New York Stock Exchange (NYSE: MUO). Pioneer Investment Management, Inc. is the Fund's investment adviser.

Please contact your financial advisor or visit www.pioneerinvestments.com.

Keep in mind, dividends are not guaranteed. Closed end funds, unlike open-end funds, are not continuously offered. There is a one-time public offering and once issued, shares of closed-end funds are bought and sold in the open market through a stock exchange and frequently trade at prices lower than their net asset value. Net Asset Value (NAV) is total assets less total liabilities divided by the number of common shares outstanding. For performance data on Pioneer's closed-end funds, please call 800-225-6292 or visit our closed-end pricing page.

Pioneer Funds Distributor, Inc., Member SIPC 

(c)Pioneer Investment Management, Inc. 60 State Street Boston, MA 02109

Member of the UniCredito Italiano Banking Group, Register of Banking Groups