Review of 26 resected ampullary carcinomas revealed intestinal type adenocarcinoma in all but one and overtly papillary carcinoma in only one case. Co-existing adenoma of the ampulla was present in 11 cases, over half of which were low-grade carcinomas. Flat duct epithelial dysplasia was present in a further eight cases, the adenocarcinoma in only two of these being well differentiated. The estimated 5 year survival rate, overall, was 52% and, with well differentiated adenocarcinoma, 75%. We recommend a new staging system, based on extent of local and lymph node spread: I = invasion confined to wall of common bile duct; II = infiltration of duodenal or retroperitoneal tissues, excluding pancreas; III = infiltration of pancreas; IV = metastasis to nearby lymph nodes. Long-term survival correlates inversely with stage, both by univariate analysis and independently of grade, so that a simple scoring system, based on a combination of both grade and stage, is an excellent predictor of the long-term outcome, defining two groups, with 5 year survival rates of 79% and 0% (P less than 0.001).