A total of 21 patients with metastatic small cell carcinoma of the prostate was treated with combination chemotherapy, either following initial hormonal therapy (15) or as initial therapy (6). Of the patients 13 (62%) had pure small cell carcinoma, whereas 8 (38%) had mixed histology of small cell carcinoma and adenocarcinoma. Patients presented with a characteristic clinical picture of a large primary mass (16 cases) with a high frequency of visceral metastases to the liver (9), lungs (7) and brain (2). The majority of the patients did not have an elevated serum prostate specific antigen (1 of 14, 7%) or prostatic acid phosphatase (2 of 21, 10%). Serum carcinoembryonic antigen was elevated in 13 patients (62%). Of the 21 patients 13 (62%) responded to chemotherapy. Survival after the diagnosis of small cell carcinoma of the prostate resulted in a median of 9.4 months with a range of 1 to 25 months. The regimens used were those considered active in the treatment of small cell carcinoma of the lung (vincristine, doxorubicin and cyclophosphamide, or etoposide and cisplatin with or without doxorubicin). Small cell carcinoma of the prostate has a characteristic clinical picture and a high response rate to cytotoxic therapy. Early introduction of chemotherapy in the treatment of small cell carcinoma of the prostate may increase the survival rate.