Research into actions of resveratrol, abundantly present in red grape skin, has been greatly stimulated by itsreported beneficial health influence. Since it was recently proposed as a potential prostate cancer chemopreventiveagent, we here performed an in vivo experiment to explore its effect in the Transgenic Rat for Adenocarcinomaof Prostate (TRAP) model, featuring the rat probasin promoter/SV 40 T antigen. Resveratrol suppressed prostatecancer growth and induction of apoptosis through androgen receptor (AR) down-regulation, without any signof toxicity. Resveratrol not only downregulated androgen receptor (AR) expression but also suppressed theandrogen responsive glandular kallikrein 11 (Gk11), known to be an ortholog of the human prostate specificantigen (PSA), at the mRNA level. The data provide a mechanistic basis for resveratrol chemopreventive efficacyagainst prostate cancer.