MHI Pioneer Municipal High Income Fund Inc

Pioneer Investments today announced the declaration of dividends for five closed-end funds for July 2009. The closing market price, annualized distribution rate and NAV distribution rate are based on data as of July 1, 2009.

Ex Date: � � � � � � � � � July 13, 2009 Record Date: July 15, 2009 Payable Date: July 31, 2009 Fund � Distribution �

MarketPrice

�

Market PriceDistributionRate

� NAV �

NAVDistributionRate

� Taxable Pioneer High Income Trust (NYSE:PHT) $ 0.1375 $ 11.22 14.71 % $ 9.71 16.99 % Pioneer Floating Rate Trust (NYSE:PHD) $ 0.0950 $ 9.51 11.99 % $ 9.97 11.43 % Pioneer Diversified High Income Trust (NYSE Amex:HNW) (a) $ 0.1900 $ 15.60 14.62 % $ 15.94 14.30 % � Tax-Exempt Pioneer Municipal High Income Trust (NYSE: MHI) $ 0.0750 $ 11.00 8.18 % $ 11.72 7.68 % Pioneer Municipal High Income Advantage Trust (NYSE: MAV) $ 0.0750 $ 10.07 8.94 % $ 10.06 8.95 % �

Taxable-EquivalentDistribution Rateat Market Price

Taxable-EquivalentDistribution Rateat NAV

Pioneer Municipal High Income Trust (NYSE: MHI) 12.58 % 11.82 % Pioneer Municipal High Income Advantage Trust (NYSE: MAV) 13.75 % 13.77 % �

Taxable-Equivalent Distribution Rate is computed using the maximum federal tax rate.

� � � � � �

(a)At this time HNW believes that a portion of this distribution may include a return of capital in addition to net investment income and long-term capital gains. A return of capital is not a distribution of income or capital gains from the fund, does not necessarily reflect the fund's investment performance, and should not be considered "yield" or "income." Further information on the composition of the distribution will be made available on the payment date and will be available at pioneerinvestments.com. The final determination of tax characteristics of the fund�s distributions will occur after the end of the year, at which time it will be reported to shareholders.

The funds are closed-end investment companies. Four of these funds trade on the New York Stock Exchange (NYSE) under the following symbols: MHI, MAV, PHT, and PHD. HNW trades on the NYSE Amex. Pioneer Investment Management, Inc. is each fund�s investment adviser.

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, common 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 � � � � � � � � � �2009 Pioneer Investment Management, Inc. 60 State Street, Boston, MA 02109 Member of the UniCredit Banking Group, Register of Banking Groups