Background: Case series suggest a possible association between bariatric surgery and incident IBD. Aim: The aim of this study was to evaluate the association between bariatric surgery and new-onset IBD. Methods: We first conducted a multi-institutional case series of patients with a history of IBD and bariatric surgery. We next conducted a matched case-control study using medical and pharmacy claims from 2008 to 2012 in a US national database from Source Healthcare Analytics LLC. Bariatric surgery was defined by ICD-9 or CPT code. Bariatric surgery was evaluated as recent (code in database timeframe), past (past history V code) or no history. Conditional logistic regression was used to estimate odds ratios (OR) and 95% CI for new-onset IBD, CD and UC. Results: A total of 15 cases of IBD (10 CD, 4 UC, 1 IBD, type unclassified) with a prior history of bariatric surgery were identified. Most cases were women, had Roux-en-Y surgery years prior to diagnosis and few IBD-related complications. A total of 8980 cases and 43 059 controls were included in our database analysis. Adjusting for confounders, a past history of bariatric surgery was associated with an increased risk of new-onset IBD (OR 1.93, 95% CI 1.34-2.79). However, patients who had recent bariatric surgery did not appear to be at shorter term risk of IBD (OR 0.94, 95% CI 0.58-1.52). Conclusion: New-onset IBD was significantly associated with a past history of bariatric surgery. This potential association needs to be confirmed in future prospective studies.