Twenty-six evaluable patients with metastatic malignant melanoma who had not received prior chemotherapy were treated in a phase II study with carboplatin (CBDCA), 400 mg/m2 iv every 4 weeks. There were five partial responses of 3, 3+, 5, 7+, and 12+ months' duration. Thrombocytopenia was the dose-limiting toxicity; ten patients had transient platelet count depressions to less than 75,000/mm3. Mild to moderate nausea and/or vomiting occurred in 15 patients. Renal, auditory, and neurologic toxic effects were not encountered. Since the response rate of 19% (95% confidence limits, 8%-38%) is similar to that noted for dacarbazine, carboplatin, singly and in combination with other agents, needs further evaluation in patients with malignant melanoma.