Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and the most common cause of liver enzyme alterations today. As regards NAFLD, it is essential to determine whether the disease presents with an inflammatory component (non-alcoholic steatohepatitis, i.e. NASH) and whether there are signs of liver fibrosis, and if so, the stage of the fibrosis. The presence of inflammation (i.e. NASH) is relevant for predicting the progression of the liver disease and the development of complications (cirrhosis and hepatocellular carcinoma), as well as in the context of presence and development of extrahepatic manifestations of NAFLD. The presence and stage of liver fibrosis is still the most important indicator in terms of progression of the liver disease itself. Non-invasive methods available today, including the most extensively studied method of transient elastography, still cannot replace liver biopsy, which remains the gold standard. As 25-30 % of the population have NAFLD, it is impractical to perform biopsies on such a large population of people. According to the recommendations of the European Association for Liver Diseases, liver biopsy is recommended for NAFLD patients at risk of developing advanced liver disease (NASH and fibrosis), particularly patients with type 2 diabetes and/or metabolic syndrome, especially those older than 50, patients who do not have a clear etiology of liver disease or are at risk of developing concurrent illnesses. Significantly elevated values of elastography parameter for fibrosis and/or elevated FIB-4 score can also help to decide which patients qualify for biopsy.