We report a rare case of a patient operated on with a diagnosis of hepatic tumour and gallstone disease, which postoperatively was found to be a hepatocellular carcinoma associated with a gallbladder carcinoma. Spiral CT at admission showed only a hepatic mass in the 4th segment, compatible with hepatocellular carcinoma and gallbladder lithiasis. Cholecystectomy was performed followed by a wedge resection of the 4th segment of the liver. The histopathological examination revealed a well-differentiated hepatocellular carcinoma and, surprisingly, an adenocarcinoma of the gallbladder confined to the mucosa. The association of a hepatocellular carcinoma and gallbladder adenocarcinoma is extremely rare. This association, together with an analysis of the literature showing the increased incidence of gallstones in cirrhotic patients and the consequent greater surgical risk when undergoing subsequent cholecystectomy after liver resection, would suggest that cholecystectomy should be performed routinely during liver resection for hepatocellular carcinoma or cirrhosis, even for minor resections and when there are no evident signs of gallbladder disease.