Eleven patients were examined by ultrasound before undergoing cholecystectomy (n = 9) or cholecystostomy (n = 2) for acalculous cholecystitis after abdominal surgery. The ultrasound images were analyzed retrospectively and compared with the surgical and histologic findings. The results indicate several established ultrasound criteria of cholecystitis to be less reliable than usual. Although 10 of 11 patients were on parenteral hyperalimentation, gross distention of the gallbladder was observed in only 3. In 4 of 7 patients, in whom pericholecystic fluid was observed, no gallbladder perforation was found at surgery. However, thickening of the gallbladder wall was displayed in 10 of 11 cases, combined with a sonolucent intramural layer in 6. Furthermore, intraluminal nonshadowing echogenic densities correlated with empyema or hemorrhage in 5 of 8 cases. In conclusion, despite several limitations, ultrasound can be of considerable help when one is deciding to perform repeat laparotomy when acalculous cholecystitis is suspected.