Twenty-three patients with disseminated bony sarcoma and 23 patients with malignant mesothelioma were evaluable in a Southwest Oncology Group (SWOG) clinical trial utilizing rubidazone and DTIC. One partial remission (PR) was observed in a previously untreated patient with metastatic Ewing's sarcoma. One patient with giant cell tumor of bone had an improvement, short of PR. Thirteen patients with osteogenic sarcoma and 23 with malignant mesothelioma had no response to this combination of drugs. The major toxic effects of therapy included nausea, vomiting, and myelosuppression, especially leukopenia; no cardiac toxicity was noted. We conclude that the combination of rubidazone and DTIC is inactive in bony sarcoma and mesothelioma.