One hundred sixty-five patients were randomized to receive either interferon alfa-n1 (Wellferon; Burroughs Wellcome Co, Research Triangle Park, NC) alone or with vinblastine. An initial six-cycle induction treatment consisted of interferon given at daily doses of 3, 5, 20, 20, and 20 x 10(6) U/m2 every 2 weeks. Vinblastine at a dose of 10 mg/m2 (later decreased to 5 mg/m2) was given on day 1 of alternate cycles. Toxicities were generally well tolerated. The overall response rate was 10% with no significant difference between treatment arms. Survival was also not significantly different for the arms. A small subset of patients (16) with metastases only to the lungs had a high complete response (CR) and partial response (PR) rate of 44%. Responses were durable, and overall survival of this group was much better than that of the other patients.