Abstract: Objective To investigate serum cytokeratin （CK18） levels in the diagnosis of patients with nonalcoholic fatty liver diseases（NAFLD）. Methods Ninety-three patients with NAFLD and forty-four healthy persons matched with age and gender were included in this study. Serum ALT,AST,GGT,CK18,FBG,FINS,TC,TG,HDL,LDL,DBP,SBP,height,weight,WC,HC,and waist hip ratio,body mass index and homoeostasis model assessment of insulin resistance were calculated. There were thirty patients with NAFLD undergoing liver bioposy. Results There was an significantly high serum CK18 levels in patients with NAFLD as compared with control subjects（P<0.001）;serum CK18 level in patients with elevated ALT group （16.38±8.1ng/ml） was higher than in normal ALT group（5.655±4.72ng/ml,P<0.001）;serum CK18 level（20.93±8.07ng/ml） in NASH group was higher than in NAFL group（7.61±5.51ng/ml,P<0.001）;Serum CK18 level was positively correlated to the degree of steatosis（r=0.527,P=0.003）,lobular inflammation（r=0.662,P<0.001）,and fibrosis（r=0.715,P<0.001）. Conclusion Serum CK18 level reflects the degree of lobular inflammation and fibrosis in NAFLD and has certain diagnostic value for NAFLD.