The increase in Non-alcoholic Fatty Liver Disease (NAFLD) and the imminent disappearance of chronic viral hepatitis thanks to new and effective therapies is motivating hepatologists to change their clinical approach to chronic liver disease. NAFLD-cirrhosis or NAFLD-Hepatocellular Carcinoma (HCC) are now the second cause of liver transplantation in the USA. This short-review is focused to the epidemiology of NAFLD/Non-alchoholic Steatohepatitis (NASH), including the definition of this disease which should be revised as well discussing the prevalence, risk factors for progression, natural history and mortality. NAFLD is considered to be the hepatic manifestation of the metabolic syndrome (MS). It affects 25-30% of the general population and the risk factors are almost identical to those of MS. The natural history involves either the development of cardiovascular diseases or cirrhosis and HCC. HCC can also develop in NASH in the absence of cirrhosis (45% of cases). We conclude that an international consensus conference on the definition, natural history, policies of surveillance and new pharmacological treatments of NAFLD and NASH is urgently needed.
