The aim of this study was to test cisplatinum and 5-FU chemotherapy. Thirty-five patients with epidermoid or undifferentiated lung carcinoma were entered in a multicentric phase II trial, in an attempt to further define the activity and toxicity of this association. None of them had been previously treated by chemotherapy. The dosage schedule was cisplatinum 100 mg/m2 D1 and 5-FU 1 g/m2 D1 to D5 every 3 weeks for 3 courses before evaluation. There were CR: 2, PR: 10, for a total response rate of 35%. Median survival was 7 months. Tolerance was acceptable. We conclude that this association can be safely administered, but that the results are not superior to others previously reported. Further studies are required to define the activity of a cisplatinum, 5-FU and radiotherapy association.