The purpose of this study was to determine the activity of a 4-drug combination chemotherapy: cisplatin, mitomycin C, vindesine and 5-fluorouracil (5-FU) in patients with advanced non-small cell lung cancer (NSCLC). Chemotherapy consisted of the administration of cisplatin (30 mg/m2 d 1-4), mitomycin C (10 mg/m2 d 1), vindesine (3 mg/m2 d 1) and 5-FU (1 g/m2 d 1-4 by continuous intravenous infusion). In patients older than 70 years, and in those who received prior irradiation or chemotherapy, cisplatin and 5-FU were omitted on day 4. Courses were repeated every 4 weeks and evaluation of response was performed after the first 2 courses. In case of response, treatment was continued until best response or untolerable toxicity. Among 182 eligible patients, 75% had received no prior therapy; 41% had locoregional disease and 59% metastatic disease; 41% lost more than 5% of their pretherapy body weight. A 34% objective response rate was observed in the 164 evaluable patients (31% in all the eligible patients) including 4 complete and 52 partial responses. Patients with locoregional disease had a significantly better response rate than those with metastases (44% vs 27%). The overall median survival was 26 weeks. Significant hematological toxicity was documented but the most serious adverse event was the occurrence of 18 (10%) cardiac or sudden deaths. These toxic deaths were significantly associated with a 5% loss of body weight prior to therapy. The addition of 5-FU to combination of cisplatin, mitomycin C and vindesine does not improve antitumoral effect but results in very significant cardiac toxicity.