All patients at Children's Hospital Medical Center who had ultrasonic evidence of cholelithiasis during the period from June 1979 to June 1982 were identified. Their charts and radiographs were reviewed, as were the surgical and pathologic reports of those who had cholecystectomy. Cholelithiasis was found to be less rare than expected. Sixty-five patients were identified during the three-year period. Exclusion of 13 patients more than 21 years old left 52 patients, 29 of whom were female and 23 male, ranging in age from 3 months to 21 years. Predisposing diseases or circumstances were present in 83 per cent of the cases. These included hemolytic anemia (15), cystic fibrosis (4), metabolic disease (3), liver disease (4), postpartum state (4), prior bowel resection or malabsorption (4), cardiac disease (4), prior orthopedic surgery (2), other (3). There were only nine cases in which no identifiable predisposition to cholelithiasis could be found. Although the gallstones were not subjected to chemical analysis, at least 53 per cent of them were visible on the 34 available abdominal radiographs, indicating the presence of calcium and thus stones of a mixed type.