 In order to provide optimal therapy for individuals with NAFLD, their liver disease must be diagnosed. The diagnostic evaluation of an individual who is suspected of having NAFLD has 3 goals. The first goal is to establish fatty liver disease as the etiology of the liver disease. Unfortunately, no specific serologic marker for NAFLD has been identified yet. Moreover, all of the current diagnostic tests for NAFLD have some limitation. Standard imaging tests such as ultrasonography and CT scan, may under- or over-estimate hepatic fat content.1,18 Moreover, detecting liver fat by abdominal imaging can neither distinguish alcoholic- from non-alcoholic-fatty liver disease, nor exclude other types of liver disease that might co-exist with hepatic steatosis. The second goal is to confirm the specific type of fatty liver disease, alcoholic fatty liver disease AFLD or non-alcoholic fatty liver disease NAFLD. These two entities cannot be distinguished by histologic parameters but only by assessment of drinking habits of the patient. The third and arguably most important, goal of the diagnostic work-up is to establish the clinical severity and prognosis of the liver disease. Because NAFLD is common and often generates few manifestations of liver disease, it is necessary to have a high index of suspicion to identify individuals who might have NAFLD. This includes individuals with the metabolic syndrome at least 2 of the following disorders: obesity, type 2 diabetes, hypertension and dyslipidemia or detection of fatty liver on an imaging study of the abdomen. Imaging studies or laboratory tests may point to advanced liver disease but early cirrhosis and NAFLD without fibrosis cannot be reliably diagnosed without liver biopsy. 