A combination chemotherapy consisting of a 72-hour continuous infusion of cisplatin (CDDP; 100 mg/m2/72 h) and 5-fluorouracil (5-FU; 3 g/m2/72 h) was conducted for inoperable non-small cell lung cancer (NSCLC). Sixty patients were accepted for this study between June 1988 and December 1990. Forty-seven patients were male (median age 68). Thirty-four patients had stage III and 26 had stage IV disease. The response rate was 25.0% (95% confidence interval, CI, 14.0-36.0%), median survival was 15.7 months. In squamous cell carcinoma, the response rate was 35.5% (95% CI, 18.7-52.3%) and median survival was 15.1 months. In non-squamous cell carcinoma, the response rate was 13.8% (95% CI, 1.2-26.4%) and median survival was 17.7 months. There was a significant difference in response rate (p < 0.01), but no significant difference in survival (p = 0.36). Grade 3 leukopenia was 11.7%, grade 3 and 4 thrombocytopenia was 13.3%. Grade 3 nausea and vomiting were 8.3%. One patient had grade 4 renal toxicity. However, there was no treatment-related death. This regimen was well tolerated. In multivariate analysis, the significant parameters were CEA, performance status and response. In conclusion, 72-hour continuous infusion of CDDP and 5-FU for treatment of NSCLC provides similar response and toxicity as previously reported regimens using CDDP.