Nonalcoholic steatohepatitis is an acquired liver disease, usually metabolic characterised by histologic lesions with steatosis, intralobular necrosis and inflammatory infiltrates. Liver biopsy findings are identical to those seen in alcoholic hepatitis. Nonalcoholic steatohepatitis is increasingly reported in industrial countries because of an increase of the prevalence of obesity and diabetes which are the most common risk factors of this disease. The diagnosis of nonalcoholic steatohepatitis is based on a confrontation between clinical and anatomic data and an exclusion of an excessive intake of alcohol and other hepatic disease. Liver biopsy has a prognosis and histologic benefit especially when there is risk factors of fibrosis. This disease is potentially severe with a potential risk for progression to cirrhosis. Progress in pathogenesis is noted but no definite therapy exist. The aim of this review is to indicate current knowledge for the gravity of nonalcoholic steatohepatitis and its consequence and to understand the pathogenesis to prevent cirrhosis.