In order to clarify important factors in prognosis of patients with gastric cancer, 3,515 surgically treated cases were investigated. The survival rate varied widely depending on the curativity which strongly correlated with the stage of the disease. For example, such cases with peritoneal dissemination and hepatic metastasis have a poor prognosis. According to our multivariate investigation by Cox's proportional hazard model (SAS, PHREG procedure) based on resectable cases of gastric cancer, the most significant prognostic factor was lymph node metastasis with a ratio of risk 4.58, followed by the macroscopic-type cancer, ratio of risk 3.61, and depth of invasion, with the ratio of risk 2.22. It should be noted that such factors as macroscopic type of cancer turned out to be an important prognostic factor aside from those related with the stage of cancer, such as lymph node metastasis and depth of invasion. Type 4 gastric cancer had a markedly poor prognosis. Among all surgically treated patients, the histologic type was insignificant as a prognostic factor, however, when limited to mucosal cancer, the undifferentiated type had a higher lymph node metastasis rate than the differentiated type. This result suggests that the histologic type of cancer should be carefully considered in case of endoscopic treatment of gastric cancer.