Though primary bariatric surgery is now firmly established as the first-line treatment for morbid obesity, this is not the case with revisional bariatric surgery. Despite proven benefits and patient demand, revisional bariatric surgery continues to attract controversy. Even though it is widely believed to be riskier and less effective than primary bariatric surgery, there is currently no systematic review in literature addressing this point. This review aims to establish outcomes after revisional bariatric surgery in comparison with those after primary bariatric surgery. Since Roux-en-Y gastric bypass or sleeve gastrectomy is currently the commonest anatomy achieved after revisional bariatric surgery, this review focuses on the outcome of revisional Roux-en-Y gastric bypass and revisional sleeve gastrectomy in comparison with respective primary procedures.