A total of 144 patients with small-cell lung cancer (SCLC) were randomized to receive cisplatin/etoposide (PE) or ifosfamide/etoposide (IE) combination chemotherapy. PE consisted of cisplatin, 80 mg/m2, intravenously (IV) on day 1, and etoposide, 150 mg/m2, IV on days 3 through 5. IE consisted of ifosfamide, 1,500 mg/m2, IV on days 1 through 5, and etoposide, 120 mg/m2, IV on days 3 through 5. Six cycles were administered in 3-week intervals. Nonresponders were switched immediately to CAV, consisting of cyclophosphamide, 600 mg/m2, IV on days 1 and 2, Adriamycin (Adria Laboratories, Columbus, OH), 50 mg/m2, IV on day 1, and vincristine, 2 mg, IV on day 1. Patients obtaining complete remission (CR) received prophylactic cranial irradiation with 30 Gy. After completion of chemotherapy, patients with limited disease received chest irradiation with 45 Gy. No maintenance therapy was given to patients in CR. Minimum follow-up was 2 years. Of the 141 patients evaluable, the overall response rate was 65% in PE therapy and 68% in IE therapy. The CR rate was 32% v 20% for all patients, 50% v 24% for limited disease, and 22% v 18% for extensive disease, all in favor of PE therapy. Median survival for all patients was 11.6 months v 9.4 months, for limited disease 14.8 months v 11.0 months, and for extensive disease 8.9 months v 7.5 months, all preferring PE therapy. The 2-year survival rate was higher in PE therapy than in IE therapy for all patients (12% v 9%) and for limited disease (23% v 10%), but not for extensive disease (5% v 9%). Median progression-free survival was 7.5 months v 6.0 months for all patients, 12.2 months v 8.8 months for limited disease, and 5.9 months v 4.4 months for extensive disease, all in favor of PE. Relapse in the area of the primary tumor was found less often after PE than after IE therapy (25% v 38%). Response to second-line CAV was seen in 30% of patients with prior PE and 43% with prior IE therapy, but was usually short lasting, and only one patient achieved CR. Toxicity included three lethal complications. Nausea, vomiting, diarrhea, and skin lesions occurred more often after PE than after IE therapy. These results suggest that PE is superior to IE chemotherapy in limited-stage, but not in extensive-stage SCLC, and that CAV is cross-resistant to PE, as well as to IE in the majority of patients.