Non-alcoholic steatohepatitis (NASH) is a chronic liver disease that occurs in patients with no significant alcohol consumption; it is not histologically different from alcoholic hepatitis because it presents macrovesicular steatosis, hepatocellular necrosis, mixed inflammatory infiltrate, and various stages of fibrosis in addition Mallory bodies in some patients. Some authors have even described NASH as a benign disease; however, it is presently considered a potentially serious disease that may evolve into liver cirrhosis and probably, liver cancer. It is more often related to female sex, obesity, and dyslipidemia, although it may be present in other population groups and associated with other factors. Its origin may be multifactorial, including insulin resistance, protein glycation, oxidative stress, and others. The disease may be asymptomatic and found in routine physical exams when the patient shows increased aminotransferases with no other explanation. At present the only specific diagnosis procedure is liver biopsy. The sole available current treatment is body weight control, normalizing glucose and lipid blood levels, as well as the administration of some medication, as illustrated in the subsequent article.