Aim To explore association between high density lipoprotein (HDL) particle size and silent myocardial ischemia (SMI) in young patients with coronary heart disease (CHD). Methods Blood samples were obtained on admission in 469 consecutive patients with CHD. Patients were divided into SMI group (n=194) and non-SMI group (n=275). General data of the patients were collected, and serum total cholesterol (TC), triglycerides (TG), low density lipoprotein-cholesterol (LDLC), high density lipoprotein-cholesterol (HDLC), apolipoprotein A1(ApoA1) and related biochemical indexes were examined. Quantitative indicator of HDL particle size was measured by HDLC/ApoA1, and other lipid parameters (TC/HDLC, non-HDLC, TG/HDLC, LDLC/HDLC) were assessed. Logistic regression analysis was performed to define the independent predictors of SMI. Results Levels of TC, uric acid, LDLC, LDLC/HDLC, TC/HDLC, non-HDL were significantly lower in patients with SMI than those in patients with non-SMI (P＜0.05). Levels of HDLC, ApoA1, HDLC/ApoA1 were significantly higher in patients with SMI than those in patients with non-SMI (P＜0.05). Results of correlation analysis showed HDL particle size (HDLC/ApoA1) was negatively correlated with Gensini scores (r=－0.405,P＜0.05). Logistic regression analysis showed that HDL particle size (HDLC/ApoA1) was independent predictor of SMI in young patients with CHD. Receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off point of HDL particle size (HDLC/ApoA1) in predicting SMI was 0.36, sensitivity was 92.1% and specificity was 75.5%. Conclusion HDL particle size (HDLC/ApoA1) have certain predictive value for SMI in young patients with CHD.