Nonalcoholic fatty liver disease (NAFLD) is among the most common causes of chronic liver disease in the western world. It is now recognized that these patients have myriad of important co-morbidities (e.g., diabetes, hypothyroidism and metabolic syndrome). The workup of patients with suspected NAFLD should consist of excluding competing etiologies and systemic evaluation of metabolic comorbidities. NAFLD is histologically categorized into steatosis and steatohepatitis, two states with fairly dichotomous natural history. While significant progress has been made in terms of noninvasively predicting advanced fibrosis, insufficient progress has been made in predicting steatohepatitis. Currently, liver biopsy remains the gold standard for the histological stratification of NAFLD. While sustained weight loss can be effective to treat NASH, it is often difficult to achieve. Foregut bariatric surgery can be quite effective in improving hepatic histology in selected patients without liver failure or significant portal hypertension. Thiazolidinediones have shown promise and the results from the ongoing, large multicenter study should become available soon. Large multicenter studies of CB, receptor anatagonists are also underway but their results will not be available for several years. Several recent studies have highlighted that cardiovascular disease is the single most important cause of morbidity and mortality in this patient population. Conclusion: Health care providers should not only focus on liver disease but also concentrate on aggressively modifying and treating their cardiovascular risk factors. (HEPATOLOGY 2009;49:306-317.)