Nonalcoholic fatty liver disease (NAFLD) – a common chronic disease of the liver, the main feature of which is the accumulation of fat in hepatocytes, is not related to alcohol abuse. NAFLD is associated with obesity, especially abdominal, metabolic syndrome and various metabolic markers of risk for cardiovascular disease and type 2 diabetes, which affects the incidence, prognosis and life expectancy of patients with obesity. This lecture describes the main causes of the disease, its pathogenesis, clinical presentation, diagnosis and treatment.