Twenty-six patients with non-small cell carcinoma of the lung and 25 with metastatic pulmonary tumors were treated by intravenous injection of 7-N-(p-hydroxyphenyl)-mitomycin C (KW2083), a derivative of mitomycin C, either at a single 70-mg/m2 dose or at a dose of 20-30 mg/m2 once a week for 3 weeks. Two patients with adenocarcinoma among 21 evaluable patients with non-small cell carcinoma of the lung, and one with embryonal cell carcinoma among 21 patients with metastatic pulmonary tumors achieved partial response lasting 5 to 7 weeks. In these three patients, KW2083 was administered by a single 70-mg/m2 dose, and no patients who received a dose of 20-30 mg/m2 weekly achieved objective response. Myelosuppression, primarily thrombocytopenia, was pronounced with either treatment regimen and it was the major dose-limiting toxicity.