Between July 2, 1987, and August 21, 1987, Cancer and Leukemia Group B (CALGB) conducted a phase II evaluation of carboplatin (CBDCA) and vinblastine (VBL) in advanced non-small-cell lung cancer. Of the 58 patients who entered the study, 55 were eligible and produced follow-up data. Chemotherapy, which was carried out in 28-day cycles, consisted of 4 mg/m2 VBL given on days 1 and 3 and 125 mg/m2 CBDCA given on days 1-3. Partial responses were observed in 10 cases (18%), and 1 patient (2%) exhibited regression of evaluable disease. No complete responses were achieved. The overall objective response rate was 20%. The median survival was 6.1 months, and the median time to treatment failure was 3.3 months. Life-threatening (grade 4) toxicity was mainly leukopenia (20%), followed by anemia (7%), infection (4%), thrombocytopenia (2%), fever (2%), nausea and vomiting (2%), and weight loss (2%). There were two deaths due to infection. The results of this study demonstrate that the combination CBDCA/VBL is active in advanced NSCLC; however, whether this combination is more active than either CBDCA or VBL alone is unknown.