Non-alcoholic fatty liver disease (NAFLD) currently represents the most common liver disease in Western countries, being found in 25-30% of the general population. NAFLD embraces a wide range of metabolic hepatic damage characterised by steatosis and, in some cases, associated non-alcoholic steatohepatitis (NASH). The long-term hepatic prognosis of NAFLD patients depends on the histological stage at diagnosis: simple steatosis has a favourable outcome, whereas patients with NASH can develop cirrhosis and other liver-related complications, including hepatocellular carcinoma. Progression of fibrosis is thought to develop in up to one third of NASH patients, including the development of cirrhosis, but regression is also possible in pre-cirrhotic stages. Independent predictors of fibrosis are older age, diabetes, obesity, hypertension, and the degree of insulin resistance. Patients with NAFLD, particularly those with NASH, have a higher prevalence and incidence of clinically manifested cardiovascular disease, independently of classical cardiometabolic risk factors. Hepatocellular carcinoma (HCC) is usually diagnosed at a late stage, but it may also occur in non-cirrhotic NASH, as obesity and diabetes both independently increases the risk of developing HCC. Liver-related mortality is increased up to ten-fold in patients with NASH.