The efficacy of postoperative adjuvant chemo- and chemoimmunotherapy in non-small cell lung cancer was evaluated in a multicentric prospective randomized study. From September 1987 to June 1990, resected lung cancer patients were randomly stratified into three groups. Group A received 2 courses of chemotherapy with CDDP and VDS following operation. Group B was administered UFT daily for 1 year after 2 courses of CDDP. Group C received intrapleural administration of OK-432 after lung resection, then UFT and OK-432 once every 2 weeks for 1 year. Out of 94 cases, analyses were carried out on 87 of eligible cases. The five-year survival rate was 56.8% in stage I (43 cases), 73.3% in stage II (12 cases), 18.8% in stage IIIA (24 cases), 50% in stage IIIB (2 cases) and 33.3% in stage IV (6 cases). The five-year survival rate in group A was 32.2%, 55.2% in group B and 53.9% in group C, and no statistical difference was recognized between 3 groups. But in the cases of noncurative resection, the 5-year survival rate was significantly low in group A compared with Group B or C. Similarly, the cases with low-grade TP (<6.0 g/dl) or low response of PPD skin reaction (< 12mm) showed a significantly low 5-year survival rate only in group A. From these results, it was suspected that aggressive chemotherapy provides no benefit for postoperative lung cancer patients with advanced disease.