SummaryObesity is associated either with hepatic steatosis, a well known and inocuous entity or with nonalcoholic steatohepatilis. This latter lesion has been recently individualized. It affects mainly middle-aged, obese women, with diabetes and/or hyperlipidaemia. It is morphologically very similar to alcoholic hepatitis. We review the literature considering I) histologic hepatic lesions of the obese, 2) epidemiologic, clinical and biological characteristics of the non alcoholic steatohepatilis, 3) evolutivity and treatment of the non alcoholic steatohepatilis and 4) present physiopathological considerations. Weconcludc by considering the clinician’s attitude in front of an obese potentially afflicted by a non alcoholic steatohepatilis.