The aldo-keto reductase 1B7 (AKR1B7) encodes an aldose-reductase which has been reported as a detoxification enzyme until now. We have demonstrated that AKR1B7 is differently expressed in various mouse white adipose tissues depending on their location. Its expression is associated with a higher ratio of preadipocytes versus adipocytes. The cells which express AKR1B7 did not contain lipid droplets and the expression level of akr1b7 was very low in mature adipocytes. We have defined the role of AKR1B7 in adipogenesis using either primary cultures of adipose stromal cells (containing adipocyte precursors) or the 3T3-L1 cell line. Under the same differentiation conditions, adipose stromal cells from tissues which expressed AKR1B7 had a decreased capacity to accumulate lipids compared to those which did not express it. Moreover, the over-expression of sense or antisense AKR1B7 in 3T3-L1 preadipocytes inhibited or accelerated, respectively, their rate of differentiation into adipocytes. In vivo experiments demonstrated that AKR1B7 encoding mRNA expression decreased in adipose tissues from mice where obesity was induced by a high fat diet. All these results attributed for the first time a novel role to AKR1B7 which is the inhibition of adipogenesis in some adipose tissues.