The physiological principle underlying biliopancreatic diversion (BPD) is attractive. It decreases food absorption and particularly that of fat. It preserves normal eating habits and is compatible with a good quality of life. Because weight loss is not a function of an imposed aversion to eating, it is more appealing to patients. Data are accumulating showing that BPD can permanently cure morbid obesity in a majority of patients and is remarkably well tolerated. While long-term systemic side-effects from decreased absorption continue to raise concerns, available results have already shown that, within 20 years, metabolic disturbances are well tolerated while weight loss and quality of life are maintained. Vitamin and mineral replacement therapy and periodic monitoring are essential. The original procedure described by Scopinaro with subsequent modifications will be presented, focusing on the duodeno-ileal switch procedure.