In an effort to test clinically the hypothesis that the duration of cellular exposure to etoposide (VP-16) and cisplatin (CDDP) is an important determinant of cytotoxicity, we performed a phase III randomized trial comparing an outpatient bolus regimen of combined VP-16 and CDDP with a sequential infusion over 72 hours of these same two drugs. All patients had stage IV non-small cell lung cancer, and survival was the primary end point. Of 113 patients randomly allocated to the study, 108 were assessable for response, survival, and toxicity. A major response was observed in 20 (37%) of 54 patients on the bolus regimen and in 16 (30%) of 54 patients receiving infusion therapy. The median time to progression was 61 and 88 days for bolus and infusion therapy, respectively. The median survival time was 148 and 157 days, respectively (P = .71). Study results were not consistent with the possibility that infusion therapy could be associated with a 50% improvement in median survival, i.e. from 5 months to 7 1/2 months. Toxicity was primarily myelosuppression and was significantly greater with the infusion regimen. We conclude that infusion therapy as tested in this protocol with VP-16 and CDDP does not offer any advantage in response rate, time to disease progression, or survival as compared with bolus therapy. In addition, infusion therapy is associated with a greater degree of neutropenia and more treatment-related deaths.