One-hundred and ninety-nine patients who had an inoperable stage III or IV non-small cell lung cancer (NSCLC) and collected were analyzed on the basis of factors affecting survival duration and response to chemotherapy. These patients were registered into a prospective randomized trial conducted from May of 1986 to April of 1988, and received either cisplatin and vindesine, cisplatin, vindesine and mitomycin C, or cisplatin and etoposide alternating with vindesine and mitomycin C. In the univariate analysis, sex, ECOG's performance status (PS), weight loss within previous 6 months, clinical stage, serum albumin value, serum lactate dehydrogenase level and hemoglobin (Hb) level were considered to be significant factors for survival (p less than 0.05). In the multivariable analysis using Cox's proportional model, clinical stage, PS, sex, weight loss and Hb level were proven to be significant variables for survival in the order of importance. When the response to chemotherapy was included in a conditional multivariable analysis, it was strongly associated with survival duration. A multivariable analysis of response using the logistic regression method demonstrated that female sex, cisplatin, vindesine and mitomycin combination regimen, squamous cell type, and no weight loss were significantly predictive of response outcome. These results are useful when comparing the response data and survival of completed studies and designing future trials in advanced NSCLC.