This study was designed to investigate issues concerning "inapparent carcinoma" of the gallbladder and the effectiveness of a radical second operation in the treatment of inapparent carcinoma. Ninety-eight patients with inapparent carcinoma were analyzed according to the "pT" category of TNM (tumor, nodes, and metastases) classification. Eighty patients underwent cholecystectomy alone, and 14 patients had a subsequent radical operation. After cholecystectomy alone it was found that (1) Patients with pT1 cancer had a 5-year survival rate (5ysr) of 100%; (2) In patients with pT2, 5ysr was 40%; and (3) Patients with pT3 showed 5ysr of 0%. Results of a radical second operation showed that (1) Patients with pT2 cancer showed a 5ysr of 90%, significantly better (p less than 0.05) than pT2 treated with cholecystectomy alone; (2) There was a prolongation of survival in patients with pT3 or pT4. It was concluded that a radical second operation should be carried out for pT2 or more advanced inapparent carcinoma, whereas follow-up without a second operation is recommended for pT1 cancer without positive margin.