A randomized controlled study was carried out on curatively resected gastric cancer patients in a cooperative study involving 16 institutions in order to evaluate the effect of an alternative long-term adjuvant immunochemotherapy using Esquinon (CQ) and Krestin (PSK). One week after surgery, CQ was given at a dose of 2mg/m2 once a week for 3 weeks and this was repeated every 6 weeks. CQ was administered intravenously in the 1st course and thereafter orally up to 9 courses. Three postoperative week, immunotherapy was then started in which PSK was given orally in 3 divided doses of 2g/m2/day from the day when CQ therapy ended for 4 consecutive weeks, and this performed for every course. Estimated survival rate and cumulative survival curves were compared utilizing the data up to 7 years after surgery in the chemotherapy group given CQ alone and in the immunochemotherapy group given CQ + PSK. The survival curve in all cases showed a favorable form in the CQ + PSK group for up to 36 months, and thereafter it crossed with that of the CQ group for up to 68 months. Both curves twisted at 68 months and then deviated from each other, showing that the effect in the CQ + PSK group beneficial. The curve showed a twisting configuration throughout the treatment period. There was no statistically significant difference between the survival curves of the two groups. Retrospective survival analysis was then performed on separate subgroups classified into the category of S1, S2, N1, and N2. The CQ + PSK group was better than the CQ alone group in its survival rate for the S1 + S2 (N1-2) group, the percentage being 11.5%, and a statistically significant difference was observed between the two groups (p = 0.089).