A phase II study of methanesulfonamide, N-(4-(9 acridinylamino)-3-methoxyphenyl)-(m-AMSA) was undertaken by the Eastern Cooperative Oncology Group. Thirty-five evaluable patients were studied, 18 of whom had had no prior therapy and eight of whom had been treated only one cytotoxic drug. Thirty-one of these patients were ECOG performance status 2 or better. The dose of m-AMSA employed in this study was 40 mg/M2 as an I.V. infusion over 20 minutes daily for 3 days, repeated every 3 weeks. Leukopenia was found to be dose-limiting; thrombocytopenia and anemia were also observed. Other prominent toxicities included anorexia, nausea, and vomiting. No cardiovascular toxicity was observed in this study, but none of the patients had received prior anthracycline therapy. Only one partial response of measurable disease was observed, all other patients had progressive disease on m-AMSA therapy. No significant clinical activity of m-AMSA against malignant melanoma was demonstrated in this very favorable group of patients.