Cholecystosonography was performed on 81 patients with known gallbladder disease who subsequently underwent cholecystectomy. Cholecystitis and/or cholethiasis was found on pathological examination in all except one. Three ultrasonographic patterns of gallstones were found: (a) internal echoes, (b) focal contour irregularities of increased sonic density, and (c) sonic shadowing. When (a) or (b) were seen in association with (c), diagnostic confidence was increased. When the gallbladder was not identified by ultrasound, a small, shrunken gallbladder or one full of stones was found at surgery. It was not possible to distinguish between normal and diseased gallbladders on the basis of diameters.