To study the potential benefit of sequential chemotherapy in inoperable small cell lung cancer (SCLC), from 1982 to 1986 ninety-one patients with histologically proven and previously untreated SCLC (median age: 53 years; median Karnofsky status: 80%) were randomly assigned to an initial therapy with adriamycin (since 1984 epirubicin), cyclophosphamide, vincristine (ACO resp. EPICO) or etoposide/cisplatin (VP16/DDP). Treatment courses were repeated every 3 weeks for a total of less than or equal to 6 courses with a crossover after a maximum of 3 cycles of either regimen. Limited disease (LD) patients with bronchoscopical, computertomographical and (re-) mediastinoscopical complete remission (CR) randomly received either a thoracic irradiation with 40 Gy or observation only. Overall, 60 out of 85 evaluable patients achieved an objective remission. A CR was observed in 24/51 patients (47%) with limited disease, and in 8/34 patients (24%) with extensive disease. Both, ACO (EPICO) and VP16/DDP were equally effective as initial and second-line therapy. Moreover, after failure to the initial therapy an objective remission could be achieved in 13% of the patients following the alternative second line combination. In 28% of LD patients with an otherwise complete remission residual tumor was detected by (re-) mediastinoscopy. Median survival times were 14 (CR: 16) months in LD patients and 10 (CR: 15) months in ED patients. At present, median survival is significantly improved in irradiated versus non-irradiated LD patients (25 vs. 13 months, p less than 0.04). The remission rates and median survival times observed in this study are comparable to those of a historical control group treated with ACO plus radiotherapy alone.