Prognostic factors for response and survival were retrospectively evaluated in 192 previously untreated patients with advanced non-small-cell lung cancer (NSCLC) who had received either vindesine plus cisplatin or mitomycin plus vindesine plus cisplatin as initial treatment. Univariate analysis demonstrated that squamous-cell histology, early stage, and a small number of metastatic sites were favorable prognostic factors for response to chemotherapy. Multivariate analysis using Cox's proportional hazard model indicated that the number of metastatic sites was the only significant pretreatment factor for response (P = 0.0005). Multivariate regression analysis revealed that the number of metastatic sites (P = 0.0002), sex (P = 0.0009), serum albumen levels (P = 0.0018), performance status (P = 0.0026) and lactic dehydrogenase values (P = 0.0026) contributed independently to survival. On the basis of these five prognostic factors, a prognostic index for survival was used to define three prognostic groupings (good, intermediate, and poor) for survival (median survival, 16.5 vs 9.4 vs 4.6 months; P = 0.0001). This particular regression model should aid in the design and analysis of new treatment strategies and may be useful for indirect comparisons of different studies carried out in similar patient populations.