Thirty-nine patients with metastatic prostate cancer refractory to hormonal manipulation were treated with vinblastine by continuous infusion. The dose was 1.5 mg/m2 daily for 5 days. A 21% response rate was obtained. Eight patients, two with visceral metastasis, one with nodal disease, and five with osseous metastasis achieved objective response. The median duration of response was 28 weeks. Myelosuppression was the major side effect: the median leukocyte count nadir was 2.8 X 10(3)/ml and the median platelet count nadir was 184 X 10(3)/ml.