Gray scale cholecystosonograms in 200 patients were reviewed. The findings in 133 of the patients were proved correct at surgery or autopsy. The overall accuracy for the detection of gallstones was 92 percent, with a false-negative rate of 4 percent. A false-positive diagnosis of cholelithiasis was made in three patients, two of whom proved to have extensive cholesterolosis. Causes of false-negative studies were the presence of a single small calculus, obesity and a large distended gallbladder. Ultrasound was specific but insensitive in the detection of a thickened gallbladder wall. The significance of a nonvisualized gallbladder by ultrasound and the role of ultrasound in the diagnosis of gallbladder disease are discussed. © 1980.