 Vitamin D VD is a pleiotropic hormone, involved in many physiological processes including calcium and phosphorus absorption. The VD metabolism begin to be well-known and involves a hepatic hydroxylation mediated by enzymes, which belong to the cytochrome P450 family leading to the production of the 25OHD, which corresponds to the circulating form of the VD. After circulation in blood, the 25OHD is submitted to a second hydroxylation in the kidney resulting to the generation of 1,25OH2D, the active metabolite of VD. Numerous epidemiological studies reported an inverse relationship between obesity and circulation level of 25OHD. Several mechanisms could explain the low level of 25OHD observed in obese subjects, the more classical evoked being based on sequestration andor dilution of VD in adipose tissue AT, the main VD storage site. However, this mechanism has never been demonstrated. In order to confirm this hypothesis, the concentration of VD and its metabolites in adipose tissue need to be quantified. 