Twenty-three patients with inoperable non-small cell lung cancer were treated with a combination chemotherapy of CDDP 100 mg/m2, ADM 30 mg/m2 and MMC 8 mg/m2 (PAM). Ten cases were adenocarcinoma, 9 cases were squamous cell carcinoma and 4 cases were large cell carcinoma. In 21 evaluable cases, partial response was obtained in 47.6%. (The response rates were 40.0% in patients with adenocarcinoma, 50.0% in those with squamous cell carcinoma and 66.7% in those with large cell carcinoma.) Leukocytopenia of less than 4,000/mm3 occurred in 100% of cases, thrombocytopenia of less than 100,000/mm3 occurred in 81.0%, and anemia(fall in hemoglobin over 2.0 g/dl) occurred in 66.7%. A transient elevation of Cr (over 1.5 mg/dl) and/or BUN (over 30 mg/dl) was observed in 23.8%. Nausea and vomiting occurred in almost all patients. No death occurred due to toxicity of PAM. These results demonstrate that PAM is an effective combination chemotherapy in patients with non-small cell carcinoma of the lung.