The purpose of this study was to investigate the efficacy and safety of combination chemotherapy using estramustine and vinorelbine in chemotherapy-naïve patients with hormone-resistant prostate cancer (HRPC). The patients (n = 54) received oral estramustine 840 mg/day on Days 1 to 14 and IV vinorelbine 25 mg/m(2) on Days 1 and 8 of every 3 wk cycle. The median number of cycles per patient was 9 (range, 1 to 27). Fifty-three patients were evaluable for toxicity and survival and 52 for prostate specific antigen (PSA) response. Median age was 68 (range, 46-80). PSA sustained decrease >50% was seen in 52% of patients (95% CI: 38-66%). A complete response was seen in 3 and a partial response in 12 of 25 patients with measurable disease, for an overall objective response of 60% (95% CI: 41-79%). Improvement in performance status was observed in 30 out of 43 evaluable for clinical benefit response. The median duration of response was 7 mo and median time to progression was 6 mo. The median survival time was 15 mo. The most common adverse event was mild gastrointestinal toxicity. In general, toxicity G3-4 was low: granulocytopenia Grade 3-4 (8%), thrombocytopenia Grade 3 (6%), and anemia Grade 3 (13%). Other Grade 3 toxicities included deep vein thrombosis (4%), hepatic (2%), cardiac ischemia (2%), fatigue (6%), and sensory neuropathy (2%). There were 2 treatment-related deaths (4%). We conclude that vinorelbine and estramustine as used in this trial is an efficacious and well-tolerated therapeutic regimen in the management of HRPC.