Ampullary carcinoma in patients under 50 years of age with a poor prognosis. Clinicopathologic features of 145 Japanese patients with ampullary carcinoma were compared among three age groups. The 145 patients were divided into three groups by the patient's age at the time of operation; there were 24 patients in group I (younger) aged less than or equal to 50 years, 99 in group II (ordinary) aged 51-69, and 22 in group III (elderly) aged greater than or equal to 70. The three groups showed no significant difference in sex, icterus, duration of icterus, size of the tumor, year of operation, macroscopic type, histopathologic type, tumor margin, lymphatic permeation, venous invasion, or pancreatic invasion. The survival curve of group I was worse than those of groups II and III. Multivariate regression analysis using 11 prognostic variables failed to reveal that the age of the patient at the time of operation was an independent factor. The younger patients aged less than or equal to 50 fared worse than the elderly patients aged greater than or equal to 70, because the group I tumors included a significantly greater number of advanced ampullary carcinoma with more frequent perineural invasion than did the group III tumors. 