Lung cancer is the most lethal cancer in the United States, with 143,000 deaths predicted for 1991. The cure rate is extremely low (approximately 13%), in part because the propensity for early spread precludes surgical cure in most patients. Thus, chemotherapy or other systemic therapies are the only way to improve the dismal results. Cisplatin is an active agent in small cell lung cancer (SCLC) and perhaps the most active agent in nonsmall cell lung cancer (NSCLC). The toxicities and inconvenience of cisplatin make it less than ideal for lung cancer therapy. Carboplatin was developed to provide a less toxic, more convenient alternative to cisplatin. The data presented in this review suggest that carboplatin may be substituted for cisplatin in the treatment of extensive-stage SCLC. In limited-stage SCLC, there are insufficient data to determine whether it should replace cisplatin when used simultaneously with chest irradiation and etoposide. It may be substituted for cisplatin in cycles not using irradiation. In NSCLC, carboplatin may be used alone or with etoposide for the palliative management of metastatic disease. Its role in earlier stages of NSCLC needs investigation.