Today, bariatric surgery combines restritive and malabsorptive procedures. Soon after surgery, bone mineral density values assessed by DXA decrease, especially at the hip but the marked weight loss could have some impact on the accuracy of the measurement. In the blood, the values of the biochemical markers of bone resorption and the parathormon are frequently increased. After bariatric surgery, the incidence of fracture is nevertheless not modified as compared to controls.