Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is an important cause of chronic liver injury in many countries around the world. The degree of liver fibrosis must be estimated to determine the prognosis, surveillance, and optimal treatment for NAFLD/NASH, similar to the situation for other liver diseases. Liver biopsy remains the gold standard for evaluating the degree of hepatic fibrosis. However, liver biopsy is an invasive and expensive method and is associated with a relatively high risk of complications. Furthermore it is impossible to enforce liver biopsy in all NAFLD patients, because the number of NAFLD patients has reached 80-100 million in the U.S. and about 5-10 million NAFLD patients are estimated to exist even in Korea. Thus, a rapid and noninvasive method of detecting fibrosis in patients with NAFLD is of major clinical interest. Several noninvasive investigations, such as serum biomarkers, scoring systems, imaging method have been developed to establish the diagnosis of NASH. First, we validated scoring systems (FIB4 index, AST/ALT ratio, AST to platelet ratio, Age-platelet index, NAFLD fibrosis score, BARD score) in biopsy-proven Asian population (n=576). Next, we investigated the clinical usefulness of ultrasound-based elastography such as transientelastography (Fibroscan) and Acoustic Radiation Force Impulse (ARFI) Elastography for detecting the advanced fibrosis in NAFLD patients. The major advantages of transient elastography and ARFI elastography, as compared with liver biopsy, are that these techniques are painless, rapid, and have no associated complications, and are, therefore, very easily accepted by the patients. It is not uncommon for patients to present with the complications of previously unrecognized cirrhosis despite being under long-standing medical care, because these patients often do not manifest the classic physical changes associated with cirrhosis. By using these noninvasive scoring systems and/or imaging methods, efficient recruitment of NASH patients with advanced stage may be facilitated.