Eight patients with sonographically demonstrated ascites adjacent to or surrounding a gallbladder wall of normal thickness are described. In two patients, improper transducer placement or angulation caused apparent gallbladder wall thickening. Two in vitro experiments, one with a balloon phantom and the other with a resected gallbladder, confirmed that wall thickness varies with transducer placement and angulation. Ascites per se neither causes gallbladder wall thickening nor results in artifactual thickening if the beam angle is controlled.