CONTEXT : Obesity is a serious disease which affects 17% of the french population. Bariatric and metabolic surgery has demonstrated its efficiency and remains the treatment of reference. Over 40,000 bariatric procedures are performed per year, mainly by laparoscopy ; the robotic approach, historically developed by Intuitive Surgical increases rapidly and accounts for 18% of the procedures in the public system. Whereas the robotic approach has demonstrated its superiority toward laparoscopy for prostatectomies and rectal resections, it still has to be demonstrated for bariatric surgery ; some studies report a decrease rate of complications for complexe procedures and selected patients but the literature remains variable and the benefit of the robot in relation to its high cost must be confirmed. OBJECTIVES: To conduct a health-economic assessment (i.e. cost-effectiveness ratio expressed as the additional cost per quality adjusted life-year gained) of the Da Vinci robot in bariatric surgery at 1 year, from the Health Care system point of view. METHOD : Randomized (482 patients), controlled, single-blind, multicenter, superiority trial comparing two approaches for primary or revisional bariatric surgery: a group benefiting from a robotic approach and a reference group benefiting from a laparoscopic approach. Data from the trial will be matched via the social security number to the French National Health Insurance Information System (SNDS database) in order to collect care consumption. The quality of life will be assessed using the EuroQol-5 Dimension (EQ5D-5L) questionnaire. PERSPECTIVES: This study will have a direct impact on patients care, professional practices and public health policy either by validating the value of the robot in bariatric surgery or conversely, by promoting the laparoscopic approach. HYPOTHESIS : Robot-assisted bariatric surgery is more expensive than conventional laparoscopy, but the additional costs associated with the robot are partly offset by a reduction in post-operative complications at 1 year, which should also help to improve patients' quality of life.