The efficacy and toxicity of two regimens based on etoposide/carboplatin with or without cyclophosphamide/vincristine in the management of small cell lung cancer (SCLC) were assessed by the Australian Lung Cancer Study Group. Response rates of 77% and 85% were noted for the two- and four-drug regimens, respectively, among patients with limited disease (LD). Response rates among patients with extensive disease (ED) were 58% and 79%, respectively. The profiles of nonhematologic toxicity were modest; myelosuppression was dose-limiting when colony-stimulating factors were not used. Twenty-six patients (14%) were older than 70 years of age. Although hematologic toxicity was more severe in the elderly group, there was no significant difference in nonhematologic toxicity, response rate, or overall survival between the geriatric and younger groups. When LD only was considered, 33% of those younger than 70 were alive at 2 years; no patients aged 70 years or older with LD were alive beyond 2 years. In patients with ED, there was no age-related difference in survival. Cytotoxic regimens based on etoposide/carboplatin constitute useful treatment for SCLC, with high response rates and manageable toxicity, irrespective of patient age.