Glutathione S-transferase pi gene methylation has recently been described in prostatic adenocarcinoma. Aggregate data on 115 samples studied to date have found an 87% sensitivity and 92% specificity for prostate cancer diagnosis. The current literature about this new marker is herein summarized, and possible molecular mechanisms by which glutathione S-transferase pi may participate in prostatic carcinogenesis are reviewed. The possible clinical implications of this molecular alteration in the diagnosis of prostatic adenocarcinoma are also studied.