Non-alcoholic steatohepatitis (NASH) is a serious form of non-alcoholic fatty liver disease (NAFLD) that can progress to advanced fibrosis, cirrhosis, and hepatocellular carcinoma. Differentiating between non-alcoholic fatty liver (NAFL) and NASH/advanced fibrosis is an important step in the management of NAFLD. Metabolic syndrome (MS) and its components are important risk factors for NAFLD, and NASH is thought to be the hepatic injury of MS. The prevalence of NASH among NAFLD patients with MS is thought to be high. In China, NAFLD is a relatively new public health concern, and the current prevalence of NASH among Chinese liver biopsy-proven NAFLD patients with and without MS is not known. This multicenter, cross-sectional study will investigate the prevalence of NASH in approximately 480 Chinese NAFLD patients. Patients will be eligible for enrollment if they have biopsy-proven NAFLD and if their liver biopsies are available for rereading. For our analysis, patients will be stratified according to the presence/absence of MS, and the prevalence of NASH in the subgroups will be compared. Other possible tests that could indicate a risk of NASH, including transient elastography, ultrasonography, cytokeratin-18, liver function tests, and others, will be studied in an effort to derive a practical, noninvasive predictive model for NASH. Patients with NAFL who have MS may also have a very high risk of developing NASH. The present study will inform about the risk of NASH in Chinese liver biopsy-proven NAFLD patients with and without MS.