© 2018 John Wiley & Sons Ltd Background: The convoluted relationship between obesity, bariatric surgery and inflammatory bowel disease (IBD) is of increasing interest. Aim: To analyse evidence regarding the role of bariatric surgery in the development of de novo IBD and its impact on clinical outcomes and safety in patients with established IBD. Methods: A PubMed/Medline search was performed to identify studies reporting the development of IBD after bariatric surgery and the outcomes of IBD patients after bariatric surgery. Results: Eighty patients were reported to have developed de novo IBD after bariatric surgery (21% ulcerative colitis [UC], 75% Crohn's disease [CD]), mostly females. Roux-en-Y gastric bypass was the most frequent bariatric technique (80%). Symptoms related to IBD occurred within 1 month and 16 years after surgery. Regarding patients with known IBD undergoing bariatric surgery, 60 patients (35 CD, 24 UC, and 1 unclassified colitis) have been reported. Sleeve gastrectomy was the most frequent bariatric procedure, particularly in CD patients. Acute flares after surgery were observed in only four UC patients. In addition, two retrospective population-based studies described perioperative outcomes of bariatric surgery on IBD patients, demonstrating only a significant increase in small bowel obstruction in these patients. Conclusions: Bariatric surgery in carefully selected patients with established IBD is technically feasible and probably safe. Development of de novo IBD should be taken into account in individuals with previous bariatric surgery who develop diarrhoea, anaemia or excessive weight loss.