One hundred fifty-six patients with metastatic or locally advanced non-small cell lung cancer (NSCLC) were randomized to 3-week cycles of treatment with either: (A) cisplatin (120 mg/m2 on day 1); (B) cisplatin (120 mg/m2 on day 1) plus etoposide (VP-16) (100 mg/m2 on days 1-3; and (C) the cisplatin plus etoposide (VP-16) regimen plus mitomycin C (10 mg/m2 on days 1, 21, and 42; then every 6 weeks for a maximum dose of 100 mg). The overall objective response rates for the combination regimens (30% with two drugs and 26% with three drugs) were superior to that obtained with one drug (4%). Likewise, the median duration of survival with the combination therapy arms (8 to 9 months) was superior to that obtained with the single agent (5 months). Both performance status and limited disease were correlated with response in all groups, and with survival in the combined chemotherapy arms. The dose-limiting toxicity was myelosuppression, especially for the group receiving the three-drug regimen. In summary, combination chemotherapy using cisplatin and etoposide (VP-16) appears to be the most active and safest regimen in NSCLC.