Patients with objectively measurable soft tissue sarcomas, osteosarcomas, chondrosarcomas, and mesotheliomas were treated with dibromodulcitol (DBD) (180 mg/m2 p.o. days 1-10 q4 wks.). ICRF-159 (300 mg/m2 p.o. tid days 1-3 q4 wks), or maytansine (MAYT) (1.5 mg/m2 I.V. q3 wks.). Forty-five evaluable patients received DBD, 47 MAYT, and 37 ICRF-159. Only patients who had had their histopathologic diagnoses confirmed by a pathology reference panel were included in the final analysis. Two patients had objective partial responses: a patient with osteosarcoma who responded to DBD and a patient with fibrosarcoma who had a partial response of brief duration to ICRF-159. Approximately 70% of the patients treated with each drug were of ECOG performance status 0 or 1, and over half had moderate or worse toxicity. It seems unlikely that these drugs have significant therapeutic activity for common mesenchymal malignancies.