Based on the report of some activity of combination therapy with dacarbazine (DTIC) and interferon alpha-2a (rIFN alpha-2a) in disseminated melanoma, we conducted a phase II study to determine the feasibility and efficacy in a large series of patients. DTIC was administered in 79 patients at the dose of 800 mg/m2 every 3 weeks and rIFN alpha-2a was given daily at the dose of 9 X 10(6) IU for the first 10 weeks and three times a week thereafter. Among the 75 evaluable patients, 25% achieved an objective response, with 8% complete and 17% partial remissions. The regression occurred within a mean time of 1.9 +/- 1.03 months from starting therapy and the mean duration of response was 8.2 +/- 4.2 months. The major side effects were vomiting, anorexia, fever, fatigue, and myalgia. There was one death related to sepsis after myelosuppression. In the other patients bone marrow and liver toxicities were not remarkable. Our data reveal that a combination regimen of rIFN alpha-2a with a cytotoxic agent has some therapeutic activity in the management of advanced malignant melanoma.