The clinicopathologic spectrum of nonalcoholic fatty liver disease (NAFLD) ranges from simple steatosis to nonalcoholic steatohepatitis (NASH). Simple steatosis has a relatively benign clinical course, but NASH can progress to cirrhosis and hepatocellular carcinoma. NAFLD occurs in the absence of significant alcohol use and is considered to be the hepatic manifestation of metabolic syndrome. NAFLD affects approximately 30% of the US population and the incidence seems to be rising as the obesity epidemic continues. At present, the most accurate modality for the diagnosis of NASH is liver biopsy; however, many patients do not have a liver biopsy, and in the absence of more-accurate imaging technologies and serum markers, the diagnosis is frequently one of exclusion. As yet there is no convincingly effective treatment for NAFLD--a multimodal treatment plan that targets obesity, insulin resistance, hyperlipidemia and hypertension might be the best option for these patients.