Based on the histological findings of 1,686 resected cases of gallbladder carcinoma and operative results collected from 172 major hospitals in Japan, the present status of radical operation was assessed with respect to the relationship between the depth of carcinoma invasion and the operative results. The depth of carcinoma invasion was classified into 5 groups, i.e., limited to the mucosal layer (m) in 11.9%, advanced to the proper muscle layer (pm) in 9.8%, extending to the subserosal layer (ss) in 29.6%, serosal involvement (se) in 21.8%, and carcinoma invading the adjacent organs (si) in 26.9%. Tumor extension, such as lymph node metastasis, invasion of lymphatic and venous vessels, and perineural infiltration, were observed more frequently in patients with ss, se, and si than in those with m and pm. The cumulative 5-year survival rates were 82.6% and 72.5% in patients with m and pm, which were significantly higher than 37.0%, 14.7%, and 7.5% in those with ss, se, and si, respectively. The choice of operative procedures should depend on the depth of carcinoma invasion. Cholecystectomy alone is done only in patients with tumor limited to the mucosa, and more radical procedures such as extended cholecystectomy should be performed in those with carcinoma invasion beyond the mucosa. Pancreatoduodenectomy is indicated in those with lymph node metastasis posterior to the head of the pancreas and with invasion to the duodenum. When the tumor directly invades the liver, major hepatic resection is recommended. Extended right hepatic lobectomy with pancreatoduodenectomy should be reserved only for those younger than 70 years of age with advanced carcinoma and in a good nutritional state because of the high postoperative morbidity and mortality.