Fourteen patients with advanced malignant melanoma were treated with a combination chemotherapy consisting of ACNU 100 mg/m2 i.v. on Day 1 in 6 week intervals and DTIC 200 mg/m2 i.v. on Days 1 to 5 at 3 week intervals. Four patients had prior chemotherapy and 2 had prior immunotherapy. Excluding 4 patients received the regimen for adjuvant chemotherapy, 10 of 14 patients were evaluable for response. There were 3 patients of partial responses, 3 minor responses, 1 no change, and 3 progressive diseases. The durations of partial responses were 1, 1, and 8 months, respectively, while the survival times in these patients were 5, 21, and 10 months, respectively. Leukopenia less than 4,000/cmm occurred in 10 of 14 patients (71%) and thrombocytopenia less than 100 X 10(3)/cmm in 9 of 14 patients (64%), moreover, these hematologic toxicities were cumulative. Serum GOT and GPT elevated to 3,460 mu/ml and 1,365 mu/ml, respectively in one patient, but this returned to a normal level one month later. Nausea and vomiting were mild to severe in 12 of 14 patients, being most marked on Day 1 and decreasing intensity during the next several days. Other non-hematologic toxicities including skin rash, fever, and phlebitis were noted in each one patient, respectively. Hematologic toxicity of this regimen was a dose limiting toxicity; therefore, intensive supportive therapy to prevent infection and hemorrhage is essential for the management of the patients during this chemotherapy.