Aim To investigate the relation between monocyte to high-density lipoprotein cholesterol ratio (MHR) and SYNTAX score in postmenopausal women with coronary atherosclerotic heart diseases (CAD). MethodsA cohort of 180 postmenopausal women was enrolled in this study, who was diagnosed as CAD by coronary angiography. The patients were categorized in three groups based on the admission MHR level:low MHR group(MHR＜0.28, n=59),moderate MHR group(0.28≤MHR≤0.43, n=61), high MHR group(MHR＞0.43,n=60). Spearman correlation and multiple linear regression were used to describe the linear association between MHR and SYNTAX score. Results The SYNTAX scores of high MHR group (25±13) were higher than low MHR group (18±13) and moderate MHR group (19±12) (P=0.003). The counts of white blood cells, counts of neutrophil and serum levels of C-reactive protein in high MHR group were higher than those in low MHR group and moderate MHR group (P＜0.001 for all comparisons). Spearman correlation analysis showed MHR was correlated with SYNTAX score(r=0.263,P＜0.001). The result of multiple linear regression indicated that SYNTAX score was affected by MHR(F=4.777,P=0.031). Conclusion This study demonstrated that MHR of postmenopausal women with CAD was significantly positively correlated with SYNTAX score. MHR may be used to predict coronary artery lesion of postmenopausal women with CAD.