The feasibility of the new classification of stage grouping by the Japanese Research Society for Gastric Cancer was evaluated. During the 22-year period between January 1975 and December 1996, a total of 1294 patients with primary gastric cancer underwent laparotomy at the Department of Surgery, Chiba University; 1222 had their lesions removed during the gastrectomy and 72 remained nonresected. Cases of direct operative death totaled 17 (1.3%). Five hundred patients (38.6%) died of a relapse of the original cancer and 42 (3.2%) died of other diseases within the followup period. Six patients (0.5%) were lost during the followup. The 5-year cumulative patient survival rates of the seven stages of the new stage grouping were distinctly proportional, and the differences were also statistically significant except between stages IIIb and IVa. The two major revised points in the new stage grouping, new classification of the depth of cancer invasion, and new stage grouping by a mosaic combination of the degree of invasion and lymph node metastasis were thus found to be reasonable based on the actuarial 5-year survival rates of the subgroups in the same stage. The present study also showed that the classification of stage IV still requires further discussion.