Gray-scale ultrasound examination of the gallbladder was successfully performed in 226 patients with sickle cell hemoglobinopathy from 2 to 18 years of age. Sixty-three (27%) demonstrated the presence of gallstones; 14 additional patients had "sludge." The incidence of gallstones increased significantly with age, from 12% in the 2- to 4-year age group to 42% in the 15- to 18-year-old group. The proportion of females with gallstones increased significantly in adolescence. Patients with gallstones had higher mean bilirubin levels, but their mean hemoglobin values and reticulocyte counts were not significantly different from those in patients without gallstones. Ultrasound examination of the gallbladder is a simple noninvasive technique for evaluating the biliary system. The incidence of gallstones in patients below the age of 10 is higher than expected and raises management questions that must be resolved.