Combinations of estramustine with other antimitotic agents, such as docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA), are synergistic in vitro and show significant clinical activity in hormone-refractory prostate cancer (HRPC). We have studied intravenous docetaxel 70 mg/m2, oral estramustine, and low-dose daily hydrocortisone in men with HRPC who demonstrated progression after initial hormone therapy. Of the 47 men who were enrolled, 40 are evaluable for response and/or toxicity. One patient (3%) has had a complete response and eight (20%) have had a partial response, yielding a total objective response rate of 23%. Of 39 patients with elevated pretreatment prostate-specific antigen levels who have had at least one posttreatment prostate-specific antigen measurement, 27 (69%) have had > or =50% decreases and 21 (54%) have had > or =75% decreases in prostate-specific antigen levels. Toxicity is modest but manageable. This therapy is efficacious and well tolerated in HRPC and should be compared in phase III trials with other drugs active in HRPC, such as mitoxantrone and hydrocortisone.