60 patients were entered into a randomised study comparing vindesine (3 mg/m2/week) plus interferon-alpha 2b (6 U/m2 3 times per week) to vindesine alone or to interferon alone for the treatment of metastatic malignant melanoma. Patients receiving the combination therapy arm (schedule A; vindesine plus interferon-alpha 2b) showed a complete and partial response rate of 8/20 (40%) which was significantly higher (P < 0.05) than that achieved with either single-agent treatment schedule. In addition, patients receiving the combined treatment schedule had a significantly prolonged survival (median 19 months) when compared to a median of 10 months for interferon alone and 5 months for vindesine alone. The combination was generally well tolerated with only additive toxicity. It is concluded that combination treatment regimens utilising interferons together with chemotherapeutic agents deserve further study in the treatment of metastatic malignant melanoma.