Abstract: Objective To investigate the etiology of patients with unexplained abnormal liver function tests. Methods Ninety-four out of 2195 patients with abnormal liver function tests were recruited in this study. The blood biochemical parameters,serology,virology,abdominal imaging and liver biopsy were performed routinely. Results The diagnosis included non-alcoholic fatty liver disease （NAFLD） in 40 case（42.6%）,autoimmune liver disease （AIH and PBC） in 22 （23.4%）,drug-induced liver injury （DILI） in 20（21.3%）,and other diseases were occult chronic hepatitis B in 3（3.2%）,and benign recurrent cholestasis,Wilson’s disease,hemochromatosis, lymphoma,cytomegalovirus infection,dysfunction of sphincter of Oddi（SOD）,Kwashiorkor syndrome and muscular dystrophy in 1 of them,and 1 still with unknown etiology. Conclusion NAFLD,ALD and DILI are the most common causes of patients with unexplained abnormal liver function tests. Genetic metabolic and other rare diseases also account for a certain proportion,which the clinicians should take attention in clinical practice.

Key words: Abnormal liver function, Etiology, Diagnosis, Liver biopsy