ABSTRACT: The degree of diagnostic radiation exposure in children with inflammatory bowel diseases (IBD) is largely unknown. In this study, we describe this exposure in a population-based sample of children with IBD and determine the characteristics associated with moderate radiation exposure.We ascertained radiological study use, demographic characteristics, IBD medication use, and the requirement for hospitalization, emergency department (ED) encounter, or inpatient gastrointestinal surgery among children with IBD within a large insurance claims database. Characteristics associated with moderate radiation exposure (at least one computed tomography (CT) or three fluoroscopies over 2 years) were determined using logistic regression models.We identified 965 children with Crohn's disease (CD) and 628 with ulcerative colitis (UC). Over 24 months, 34% of CD subjects and 23% of UC subjects were exposed to moderate diagnostic radiation (odds ratio (OR) 1.71, 95% confidence interval (CI), 1.36 - 2.14). CT accounted for 28% and 25% of all studies in CD and UC subjects, respectively. For CD subjects, moderate radiation exposure was associated with hospitalization (OR 4.89, 95% CI 3.37 - 7.09), surgery (OR 2.93, 95% CI 1.59 - 5.39), ED encounter (OR 2.65, 95% CI 1.93 - 3.64), oral steroids (OR 2.25, 95% CI 1.50 - 3.38), and budesonide (OR 1.80, 95% CI 1.10 - 3.06); an inverse association was seen with immunomodulator use (OR 0.67, 95% CI 0.47 - 0.97). Except for oral steroids and immunomodulators, similar relationships were seen in UC.A substantial proportion of children with IBD are exposed to moderate amounts of radiation as a result of diagnostic testing. This high utilization may impart long-term risk, given the chronic nature of the disease.