OBJECTIVE. The objective of our study was to evaluate ultrasound images of pediatric patients with choledochal cyst perforation and establish imaging findings that can be used as the basis for timely surgical intervention. MATERIALS AND METHODS. Our study group was composed of 23 pediatric patients who presented with various symptoms of acute abdomen and were admitted to our institution between 1996 and 2013. All had undergone preoperative ultrasound examination and had a final diagnosis of choledochal cyst perforation that was confirmed at exploratory laparotomy. The imaging and surgical data were reviewed and analyzed retrospectively. RESULTS. The 23 patients included nine males and 14 females with a mean age of 2.55 years and mean disease duration of 12.48 days. The most common initial diagnoses were intestinal obstruction and peritonitis. Real-time ultrasound imaging with multislice views revealed characteristics of choledochal cyst perforation, including changes in the shape of the bile duct, loss of local gallbladder tension, thickened gallbladder wall, changes in the morphology of the gallbladder, and peritoneal effusion. The inability to visualize the gallbladder, gallbladder enlargement, the presence of gallbladder sludge and of pebblelike stones, and dilatation of the intrahepatic ducts were also noted on ultrasound. Choledochectasia was present in a majority of the patients (17/23), and ascites was seen in all 23 patients. The ultrasound signs corresponded to the surgical findings, thus showing the high clinical diagnostic value of ultrasound in this setting. CONCLUSION. Real-time ultrasound imaging-with its multislice views and good reproducibility-allows definitive preoperative diagnosis of pediatric choledochal cyst perforation.