Clinicopathological studies were carried out in fifty nine surgical cases of carcinoma of Vater's ampulla. In the point of view of the developmental process of the carcinoma, they were divided into the following two types; tumor-forming type and ulcerative type. No significant difference in survival time was noticed between two types. In the ulcerative type, prognosis was much better in the cases of carcinoma with small ulcer than those of carcinoma with large ulcer. The "early cancer" in which carcinoma did not extend beyond the sphincter of Oddi showed better prognosis than the "advanced cancer" in which carcinoma infiltrated into the pancreas. There were 10% of vascular permeation and 20% of metastasis into lymph nodes in the "early cancer", while there were 92% of vascular permeation and 71% of metastasis into lymph nodes in the "advanced cancer". Although high incidence of positive tissue-CEA (28 out of 34 cases, 82.4%) was observed, 9 out of 19 cases (47.4%) showed slight increase of serum-CEA level. The diagnostic value of serum-CEA seemed to be relatively low in carcinoma of Vater's ampulla.