Five cases of primary carcinoma of the gallbladder are presented. The cases were identified after a study of 802 cholecystectomies in a period of 5 years. The patients are three women and two men between the ages of 43 and 60 years (mean, 55.8 years). In three cases the clinical diagnosis was that of carcinoma, while in two other patients the clinical diagnosis was that of acute cholecystitis. Grossly, all cases were characterized by a gray-white diffuse or focal plaque-like thickening of the gallbladder wall, with loss of the normal velvety mucosal surface and fibrosis of the organ. Histologically, four cases belong to moderately to poorly differentiated adenocarcinoma and were characterized by infiltrative, irregularly shaped and sized glands, islands, nests, and cords. The cells showed pleomorphic nuclei with clumped chromatin and frequent single nucleoli. One case was a mucinous adenocarcinoma characterized by large pools of mucoid material with neoplastic glands and cells ''floating'' within. Pathologic staging was pT3 in three cases; pT2 in one case; and pT2N1 in one other case. The present study highlights the importance of careful gross and histopathologic evaluation of gallbladders otherwise removed with the history of chronic or acute cholecystitis. In addition, it highlights the incidence of gallbladder carcinoma in a particular institution.