A study of postoperative adjuvant chemotherapy according to cell type, combined with immunotherapy using PSK and OK-432 was conducted in 178 lung cancer patients who had undergone resection. BRM (PSK or OK-432) was selected by randomization. Chemotherapy was mainly performed with VCR, MMC, and MTX except for small cell carcinoma. Of the total number of lung cancer cases, 113 were evaluable. Four-year survival rates were 36.7% for the OK-432 group, 55.9% for the PSK group and 34.7% for the control group, with significant differences among these three groups. Survival rates for stage III showed significant differences between immunochemotherapy groups, (OK-432 group, PSK group) and the chemotherapy group. Postoperative administration of immunomodulators is therefore considered to contribute to the improved survival of patients in lung cancer.