Background: Bariatric surgery has a major role in treatment of obesity for patients with a history of unsuccessful trials to lose weight, as it gives the most successful results in improving quality of life. Aim and objectives: The aim of this study was improvement of quality of life (QOL) through assessment of QOL among bariatric surgery patients. Methods: A case control study was conducted on 3 groups (32 participants in each group), Bariatric surgery individuals (12-18 months after surgery), Obese on diet individuals and Obese without diet individuals at Zagazig city from the beginning of Dec. 2019 to the end of Sep. 2020. QOL was assessed using MAII and SF36 Questionnaires. Results: The mean age was 32.41 ± 7.51 years. Females were about 3/4 of all groups. Most of the studied bariatric surgery group had gasterectomy surgery and Gastric Bypass (68.8 % and 15.6 %) respectively. The percentage of patients with good to very good quality of life outcomes (28.1%) was significantly higher in Bariatric surgery group. All components of the SF-36 were higher in patients subjected to bariatric surgery than in the obese on diet and obese without diet. Conclusion: Bariatric surgeries are very successful and provide more positive results in weight loss and improving quality of life than regular dietary regimens