Shareholder Proxy Services ------------------------------------------------------------------------------- September 15, 2009 IMPORTANT MATTER REG1 ---- REG 2 ----- REG 3 ----- REG 4 ----- REG 5 ----- REG 6 ----- REG 7 ----- Re: Pioneer Diversified High Income Trust (NYSE Amex: HNW) Cusip: 723653101 Dear Shareholder: Our firm has been retained by Pioneer Diversified High Income Trust to contact you regarding your investment in common shares of the Trust, as of record date July 9, 2009. We have attempted to contact you, but have yet to be successful. Please contact us immediately at 1-800-232-1064 between the hours of 9:00 a.m. and 11:00 p.m., Eastern Standard Time. Thank you in advance for your assistance with this matter. Sincerely, Fred Bonnell Investor Relations Supervisor Shareholder Services The Altman Group ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- "tag id" ------------------------------------------------------------------------------- 60 East 42nd Street, New York, New York 10165