Objective: The aim of this study was to evaluate gallbladder motility in constipated children. Patients and Methods: A cross-sectional study was conducted on pediatric patients with refractory constipation examined in a pediatric gastroenterology unit of a teaching hospital between January 2005 and August 2006. All of the patients seen during the period were included (age range, 2-16 years). The control group, matched for sex and age, was selected among patients seen at the same basic health units where patients were seen before being referred to pediatric gastroenterologists. A gallbladder contractility index was calculated based on fasting and postprandial gallbladder areas, using an ultrasonographic method. Ultrasonography studies were performed prospectively and blindly by the same physician. Measurements obtained in patients were compared with those obtained in controls. Results: A total of 132 constipated children and the same number of healthy controls were included in the study. Median and mean fasting gallbladder areas were similar in patients and controls. Postprandial gallbladder areas were larger 2 in the patient group, mean +/- SD = 594.8 +/- 206.4 mm(2), median, 2 562.5 mm(2), than in the control roup, mean +/- SD = 541.1 +/- 156.1 mm(2), median, 530.5mm(2); P=.031. Logistic regression showed that the risk of a contractility index <25% was 5.2 times greater in patients (odds ratio [OR] 5.2; 95% confidence interval [CI] 2.5-10.81) than in controls. Age was found to be a protective factor (OR 0.79; 95% CI 0.71-0.88). Conclusions: Gallbladder motility disorder was identified in a group of children with severe constipation. This finding may contribute to the understanding of functional constipation in children.464414418