The decarbazine analogue CB10-277 has been investigated for anti-tumour activity in a phase II study on malignant melanoma. Treatment was administered as a slow infusion of 12,000 mg m-2 over 24 h and repeated every 3 weeks. A total of 28 patients were entered into the study, of whom 23 were eligible for review. A total of 64 courses was given. There was one objective partial response in 22 patients assessable for response. The major toxicities were leucopenia and thrombocytopenia. CB10-277 in this schedule therefore does not appear to have major activity in melanoma.