Nonalcoholic fatty liver disease (NAFLD) is the most common cause of abnormal liver tests in the United States. NAFLD is often found in association with obesity and diabetes and it is expected to become increasingly prevalent as the incidence of diabetes and obesity continues to increase. NAFLD represents a range of diseases from simple fatty deposition in the liver to more aggressive inflammation and fibrosis, termed nonalcoholic steatohepatitis (NASH). The distinction of NASH as an entity within NAFLD is an important one, as the natural history of this disease is different. Ultimately, NASH may progress to cirrhosis in up to 25% of patients, compared to simple steatosis which is a benign condition.