Small cell lung cancer requires aggressive combination chemotherapy. The three active agents, doxorubicin (A) 45 mg/m2 i.v. day 1, cyclophosphamide (C) 1.0 mg/m2 i.v. day 1 and VP16-213 (E) 50 mg/m2/day i.v. days 1-5 were given together. The combination (ACE) was given every 21 days without chest irradiation. One hundred and seventy-four patients have been stratified for extent of disease and randomized on three sequential studies testing ACE vs ACE + MER immunotherapy (38 patients), or ACE vs ACE alternating with CCNU, methotrexate, vincristine and procarbazine (109 patients), or ACE vs ACE II (ACE with continuous VP16-213 - 100 mg/m2/day X 5 days - 27 patients - ongoing). The immunotherapy and the alternating non-cross resistant combination have not proven beneficial with respect to response or survival. The ACE combination, regardless of additional treatments, has produced greater than 90% response overall. In limited disease the complete response (CR) frequency is 65%. The median survival for limited disease overall is 14 months and 18 months for patients achieving CR. In extensive disease the CR frequency is 40% with a median survival of 9 months overall and 13 months for patients achieving CR. Response frequency and survival are identical in the first two studies and 20-30% of patients with limited disease are long-term survivors with one late relapse (greater than 3 years). Patients who achieved CR had a significantly longer survival regardless of other factors such as performance status or extent of disease. Prophylactic cranial irradiation was demonstrated to be useful in prevention or delaying CNS metastases in patients who achieved CR. The third generation study of high-dose VP16-213 infusion seeks to increase the CR frequency. ACE chemotherapy without chest irradiation is a highly effective treatment for all patients with small cell lung cancer and compares favorably with all other studies with or without adjuvant radiotherapy.