In order to compare the efficacy and toxicity of cis-platinum and mitomycin C in advanced non-small cell lung cancer (NSCLC), randomized trial has been conducted since June 1982. Forty-eight previously untreated patients with advanced NSCLC were administered either PVB (a combination of cis-platinum, vindesine, and bleomycin) or MVB (mitomycin C, vindesine, and bleomycin), and 47 of them were fully evaluated for tumor response and toxicity. The partial response rate was 35% for 23 patients receiving PVB compared to 29% for patients treated with MVB. The projected median survival time were 10.0 months for PVB, and 8.5 months for MVB. There were no statistical differences in response rate and survival time between PVB and MVB. Myelotoxicity and neurotoxicity were comparable for the two treatments. Upper G.I. toxicity and nephrotoxicity were significantly more frequent in patients given PVB than in those receiving MVB, but these toxicities were generally mangeable. Cis-platinum thus appears to have no significant advantage over mitomycin C in the treatment of advanced NSCLC.