One hundred nine patients with limited small cell lung carcinoma were entered in a phase II study of treatment consisting of alternating 6 cycles of combination chemotherapy and 3 courses of mediastinal radiotherapy. Chemotherapy consisted of 40 mg doxorubicin/m2 on day 1; 75 mg etoposide/m2 on days 1, 2, and 3; 300 mg cyclophosphamide/m2 on days 3, 4, 5, and 6; and 400 mg methotrexate/m2 on day 2 (plus folinic acid rescue) or 100 mg cisplatin/m2 on day 2. The total mediastinal radiation dose was 45 or 55 Gy. A 6- to 8-cycle maintenance chemotherapy followed this induction protocol. The complete remission rate at the end of the induction therapy was 79%. The local recurrence rate was 25%, and the distant metastases rate was 52%. Median survival is 17.2 +/- 1.2 months and survival rate at 3 years is 26%. Lethal toxicity occurred in 3% of the patients, and long-term survivors are being evaluated. Our results justify further investigations with this alternating schedule.