Abstract: The aim of this study is to study the relation between gallbladder stones disease and different operations for weight reduction. Methods: This retrospective study included 100 participants above 18 years old after surgery for morbid obesity. Data was collected from the patient records, including the preoperative data (preoperative weight and type of surgery) and postoperative data (amount of weight loss and its rate, gallbladder stones formation or its complications). Results: From the total studied 100 participants; 29 patients had symptoms of cholecystitis, 11 of them had gall bladder stones and 18 cases were asymptomatic. There were 71 patients asymptomatic; however 8 patients among them had gall bladder stones detected by US. There was no significant difference between different types of operations as regards symptoms of cholecystitis. Conclusion: When evaluating the occurrence of gallbladder stones following bariatric surgery, the degree of weight loss exceeding 25% of initial body weight within the first half-year following surgery was considered a significant risk. More gallstones are forming from gastric bypass surgery than from pure restrictive surgery, such as sleeve gastrectomy, in patients with BMIs more than 40 kg/m2.