Several new developments promise to improve the lot of the morbidly obese. Perhaps the most important of these is the gradual recognition that morbid obesity is a serious illness that is not the result of immorality or gluttony but is, in most cases, a disabling genetically determined handicap. The second advance was the agreement at the National Institutes of Health Consensus Conference, March 25-27, 1991 that medical therapies generally fail to control severe obesity and that surgery should be considered for those individuals who have a body mass index over 40 and, if the comorbidities of obesity, such as diabetes or sleep apnea, are present, to consider surgical intervention when the body mass index is greater than 35. The third development has been the improvement of bariatric surgery, ie, the surgery for morbid obesity, with better operations, better quality controls, and rigorous follow-up. This article reviews the newer concepts of morbid obesity as a disease, delineates the indications for surgery, describes the currently recommended operations, and presents the risks and benefits of these procedures.