Nonalcoholic liver disease (NAFLD) is a hot topic for gastroenterologists and hepatologists and clinical practitioners must be kept abreast with the rapid progress of knowledge in this field. The Romanian Society of Gastroenterology and Hepatology (RSGH) has elaborated this review dedicated to evidence-based data on pathogenesis, diagnosis and therapy of this condition. The term NAFLD includes two distinct conditions, with different histologic features and prognosis: non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH), the second with the highest risk of evolution to cirrhosis and its complications, including hepatocellular carcinoma (HCC). Non-alcoholic fatty liver disease is considered the hepatic manifestation of the metabolic syndrome. Therefore, NAFLD is associated not only with an increase of liver-related mortality, but also of the overall mortality, especially cardiovascular and malignancies. Noninvasive techniques, such as biological tests and elastography can be used for the evaluation of NAFLD patients. Liver biopsy should be recommended in selected cases, for diagnostic, therapeutic and prognostic purposes. Patients with NAFLD would benefit from their lifestyle changes by progressive weight loss through exercise and low fat and sugar diet. Pharmacotherapy should be reserved for patients with NASH, particularly for those with significant fibrosis. Until now, there are no FDA approved therapies for NASH.