Abstract: Objective To assess the overall and sex-specific correlations between serum cystatin C（Cys-C） and metabolic syndrome（MS） among rural Uygur residents in Xinjiang, providing a reference for the prevention and treatment of MS. Methods From July to August 2010, 3 775 rural Uygur residents aged 18 and above were selected from 12 villages in Kashgar, Xinjiang by stratified cluster random sampling. Data were collected by questionnaire survey, physical examination and laboratory test. The serum Cys-C level was compared between the residents with different MS components. The correlation between serum Cys-C and MS was analyzed by multivariate logistic regression analysis. The receiver operating characteristic（ROC） curve was applied to assess the predictive value of Cys-C for MS. Results Among all participants, the MS group showed a higher level of Cys-C than the non-MS group （1.04±0.25） vs（0.93±0.31） mg/L,t=-9.658,P＜0.001. The subjects with one of the components of MS abdominal obesity, hyperglycemia, increased blood pressure, elevated triacylglycerol and decreased high density lipoprotein cholesterol（HDL-C） showed higher Cys-C levels than those without（P＜0.01 for all）, except for males and females with reduced HDL-C and males with hyperglycemia. Males showed higher levels of Cys-C than females regardless of the prevalence of MS or one of its components. After adjusting for confounders, multivariate logistic regression analysis showed that the risk of MS increased with the level of serum Cys-C in males（χ~2=12.426, P=0.006）, but this trend was not significant among females. The optimal cutoff value of serum Cys-C for predicting MS in all participants was 0.87 mg/L, which yielded a sensitivity of 79.9% and a specificity of 41.8%. And the values of the area under the ROC curve（95%CI） for Cys-C predicting MS in all participants, females and males were 0.627（0.611-0.642）, 0.652（0.618-0.687）, and 0.582（0.550-0.613）, respectively（all P＜0.001）. Conclusions Cys-C is closely related to MS in rural Uygur in Xinjiang. The risk of MS in males increases with the increase of Cys-C level.