Iv Baker's antifol (BAF) (250 mg/m2/day X 3 consecutive days) was administered to 34 patients with metastatic sarcoma. All patients had received extensive prior therapy including prior chemotherapy and had progressive disease at the start of the study. Liver and renal functions were normal in all patients. Of 29 patients evaluable for response, 25 demonstrated progressive disease and four had stable disease for periods of from 1 to 6 months. No objective responses were observed. The other five patients died from 3 to 12 days after initiation of therapy. Toxicity included myelosuppression of significant degree in nine patients, gastrointestinal effects of nausea and vomiting in seven, stomatitis in three, and dermatitis in four. Most toxicity was mild to moderate, although one drug-related death due to marked myelosuppression was seen. In conclusion, BAF is considered to be insignificantly active in the secondary treatment of metastatic sarcomas at the dose and schedule studied.