Limited studies in patients with inflammatory bowel disease (IBD) suggest that anti-TNF therapy may be associated with excessive weight gain. The objective of this study was to compare the change in BMI z-score in children with Crohn Disease (CD) on anti-TNF therapy (CD exposed) to those not on anti-TNF therapy (CD unexposed) over time. We also sought to determine if anti-TNF exposure is a risk factor for excessive weight gain and obesity.