Abstract: Objective To investigate the relationship between serum alanine aminotransferase(ALT)and metabolic syndrome(MS)and its components.Methods A rural residents sample was selected in Wujin district of Changzhou city with multi-stage cluster sampling method for a study including questionnaire survey, physical examination and laboratory test.Results Among the 8 818 residents, the prevalence of MS, central obesity, elevated blood pressure, elevated fasting blood glucose(FBG), elevated triglycerides(TG), and decreased high-density lipoprotein cholesterol(HDL-C)were 21.62%, 37.02%, 53.00%, 26.86%, 32.24%, and 18.04%, respectively.The average ALT level was 22.43±17.71 U/L and the prevalence of MS, central obesity, elevated blood pressure, elevated FBG, elevated TG, decreased HDL-C were increased with ALT quartiles in the residents(P<0.001 for all).Multivariate logistic regression analyses showed that the risk of MS was increased with ALT quantile levels after adjusting for age, sex, smoking, alcohol consumption, and education level, with an odds ratio(OR)of Q₄ group of 5.69(95%confidence interval95% CI=4.72-6.86)compared to Q₁ group.The risk of central obesity, elevated blood pressure, elevated FBG, and elevated TG increased with ALT quantile level after adjusting for central obesity, elevated blood pressure, elevated FBG, elevated TG, decreased HDL-C, with the OR of 3.20(95%CI = 3.20-3.75), 1.36(95%CI = 1.36-1.58), 1.87(95% CI =1.87-2.20), and 3.52(95%CI = 3.52-4.15) for Q₄ group compared to Q1 group.Conclusion Serum ALT level is associated with MS and its components and serum ALT level may be a predictor of MS.