To evaluate the efficacy of adjuvant immunochemotherapy, especially the long-term administration of HCFU to patients with noncuratively resected and unresected gastric cancer, a randomized controlled study was conducted by 16 institutions in Hokkaido. After surgery, 185 patients were divided into two groups using the envelope method; group A (84 patients) treated by MMC (4 mg, twice a week, total 1 mg/kg)+OK-432 (or PSK): group B (101 patients) treated with MMC+OK-432+HCFU (600 mg, per day). The 5- and 10-year survival rates were 9.8 and 3.1% in group A, and 11.1 and 11.1% in group B (p=0.062). Better survival rates were obtained in those cases with unresected, S3, or peritoneal dissemination in group B. These results suggested the long-term administration of HCFU was effective for noncuratively resected and unresected gastric cancer.