Conservative therapy results almost always in failure in the morbidly obese patient. Bariatric surgery is currently the only treatment associated with sufficient and sustained weight loss. The role of obesity surgery has markedly increased since the development of laparoscopic techniques. Proximal gastric bypass is currently the procedure of choice. It is followed by an excess weight loss of approximately 60-70%, and is effective in over 80% of the patients. In Switzerland, access to surgery is limited to patients with a BMI >40 kg/m2. Preoperative evaluation is of paramount importance, and so is patient instruction and teaching before surgery. After bariatric surgery, life-long follow-up by a specialized team is essential.