A phase II trial was conducted to determine the efficacy and toxicity of the addition of interferon-alpha 2b (IFN-alpha) to the chemotherapy combination of dacarbazine (DTIC), carmustine (BCNU), cisplatin and tamoxifen (DBCT), in patients with stage III or IV melanoma. Treatment consisted of DTIC 220 mg/m2 and cisplatin 25 mg/m2 intravenously on days 1-3, BCNU 100 mg/m2 IV on day 1 only, tamoxifen 20 mg orally twice daily and IFN-alpha 5 x 10(6) units/m2 subcutaneously on days 1-5. Cycles were repeated every 4 weeks. All patients received a loading dose of tamoxifen 100 mg orally twice daily for 5 days before the first course of therapy. Of the 24 patients treated, three (13%) achieved a complete response (CR) and six (25%) a partial response (PR), for an overall response rate of 38% (95% confidence interval, 17-58%). Two patients, one who achieved a clinical CR and one a PR, had pathologically confirmed complete responses. Severe myelosuppression occurred in 47% of cycles and constitutional symptoms were common. Overall, the addition of IFN-alpha to the DBCT regimen did not appear to enhance the response rate and may have increased toxicity.