Non-alcoholic fatty liver disease (NAFLD) covers a wide spectrum of liver pathology--from steatosis alone, through the necroinflammatory disorder of non-alcoholic steatohepatitis (NASH) to cirrhosis and liver cancer. NAFLD/NASH is mostly related with visceral adiposity, obesity, type 2 diabetes melitus (DM t.2) and metabolic syndrome. Pathogenetic concepts of NAFLD include overnutrition and underactivity, insulin resistance (IR) and genetic factor. The prevalence of NAFLD has been estimated to be 17-33% in some countries, NASH may be present in about 1/3 of such cases, while 20-25% of NASH cases could progress to cirrhosis. NAFLD is now recognized as one of the most frequent reason of liver tests elevation without clinical symptoms. Insulin resistance is considering as having a central role in NAFLD pathogenesis. In hepatocytes, IR is related to hyperglycaemia and hyperinsulinaemia, formation of advanced glycation end-products, increased free fatty acids and their metabolites, oxidative stress and altered profiles of adipocytokines. Early stages of fatty liver are clinically silent and include elevation of ALT and GGTP, hyperechogenic liver in USG and/or hepatomegaly. Among clinical symptoms, abdominal discomfort is relatively common as well as chronic fatigue. NAFLD/NASH is not a benign disease, progressive liver biopsy have shown histological progression of fibrosis in 32%, the estimated rate of cirrhosis development is 20% and a liver--related death is 12% over 10 years. No treatment has scientifically proved to ameliorate NAFLD or to avoid its progression. The various therapeutic alternatives are aimed at interfering with the risk factors involved in the pathogenesis of the disorder in order to prevent the progression to end-stage liver disease. The most important therapeutic measure is increasing insulin sensitivity by an attempt to change a lifestyle mostly by dieting and physical activity in order to loose weight. The most used agent is metformin, the others are under controlled trials or their effectiveness is low. NASH is not a common indication for liver transplantation because of the older age distribution of patients and high prevalence of comorbidity, related to metabolic syndrome. Recurence of NASH in the grafted liver is also a relatively frequent complication.