The Japan Pancreas Society (JPS) published the fifth Japanese edition of the General Rules for the Study of Pancreatic Cancer in 2002, the same year that the Union Internationale Contre le Cancer (UICC) published its sixth edition. The JPS fifth edition had been revised, based on data from 18,629 cases of carcinoma of the pancreas registered by the JPS (1981-1996) with the goal of making the General Rules simple, easy to understand, and reliable for predicting outcome. The 2 classifications are compared by analyzing the data on 3979 resected patients with tubular adenocarcinoma of the pancreatic head registered by the JPS, focusing on the reliability of predicting outcome. In the extent of the primary tumor (T category), survival rates differed significantly among the 4 groups (T1, T2, T3, T4) in the JPS and UICC classifications. In the extent of lymph node metastasis (N category), survival rates differed significantly among the 4 groups (N0, N1, N2, N3) in the JPS classification and also did significantly between the 2 groups (N0, N1) in the UICC classification. In the stage grouping, however, 2 classifications differed considerably. More than half of the cases of UICC stage II are equivalent to JPS stage IV. Comparison of survival curves according to stage reveals that stratification is much better in the JPS classification than in the UICC classification. These results indicate that the JPS classification is more reliable for predicting outcome as compared with the UICC classification.