Since cytotoxic chemotherapy (BCNU, DTIC and cisplatin, tamoxifen) and interferon-alpha (IFN-alpha) have each produced responses in advanced malignant melanoma, a phase II trial was conducted to evaluate the response and toxicity of simultaneous administration of both therapies. Of 33 assessable patients, two (6%) had complete response (CR) and 12 patients (36%) had partial response (PR), for a total response rate (CR+PR) of 42% (95% confidence interval 26-58). Four patients had minor response (12%). Mixed responses occurred in five patients (15%). The remaining patients had progressive disease. The duration of CR was 3, 7 and 17 (+) months and the duration of PR was 3+ to 19+ months (median 6 months). The median overall survival for all patients entered into the study was 5 months. Main toxicities included myelosuppression and fatigue. Combined simultaneous cytotoxic chemotherapy and IFN produced a high response rate (42%) which is comparable to that reported for chemotherapy alone. Further studies are needed to determine the optimal schedule for combining chemotherapy and immunotherapeutic agents as well as the impact of biological agents on survival in the treatment of melanoma.