Thirteen gall bladders presenting normal findings, cholesterolosis, chronic cholecystitis, mucosal hyperplasia and adenomyomatosis were studied by scanning and light microscopy. In the bladder of patients with cholesterolosis the mucosal folds were clearly dilated, but the individual epithelial cells had preserved their normal hexagonal structure. In the gall bladder of one patient with cholesterolosis, goblet‐like cells were seen in the epithelium. The greatest changes were seen in material from patients with chronic cholecystitis, in which the mucosal folds were clearly flattened and the cell boundaries indistinct and small polypoid structures were seen on the surface of the epithelium. No special changes were seen in material obtained from patients with adenomyomatosis or mucosal hyperplasi