BACKGROUND: The survival benefit of combination chemotherapy comparing supportive care to patients with advanced non-small cell lung cancer, especially stage IV non-small cell lung cancer patients with metastatic disease, is controversial. The main goal of this study was to evaluate the difference in survival between patients treated with chemotherapy and those who were not and to identify prognostic factors in the patients with stage IV non-small cell lung cancer. METHODS: From January 1989 to December 1994, total 67 patients including 20 patients treated with combination chemotherapy and 47 patients treated with only supportive care in stage IV non-small cell lung cancer patients with metastatic disease were enrolled in this study. Combination chemotherapy consisted of etoposide 120mg/m2 iv for 3 days and cis-platin iv day 1 every 4 weeks. The treatment groups were retrospectively analyzed by age, sex, histologic cell type, weight loss, serum LDH level, ECOG performance status and major organ metastasis. RESULTS: The significant prognostic factors influencing survival on this study were ECOG performance status and histologic subtype. Overall response rate by combination chemo-therapy was 30%(complete response 0%, partial response 30%). Median survival of overall patients was 13.6 weeks and median survival of chemotherapy group, 20 weeks, was significantly longer than that of supportive care group, 11.7 week(p<0.01). Median survival of responder in patients receiving chemotherapy, 45.5 weeks, was significantly longer than that of non-responder, 17.3 weeks(p<0.05). 1 year-survival rate of chemotherapy group and supportive care group was 15% and 8%, respectively. Nausea or vomiting, alopecia and anemia were seen in nearly most cases after this combination chemotherapy. Toxicities above grade 3 included neutropenia, anemia, thrombocytopenia, infection, fever, nausea, vomiting and alopecia. But this combination chemotherapy was relatively well tolerated except one treatment-related death from sepsis associated with severe granulocytopenia. CONCLUSION: These results suggest that systemic chemotherapy might be helpful to the stage IV non-small cell lung cancer patients with good performance status and large scale randomized prospective trials should be performed.