Background:The level of high-density lipoprotein cholesterol (HDL-C) is an important risk indicator and used in risk factor counting and quantitative risk assessment;however,the effect of HDL-C in young male patients with acute myocardial infarction (AMI) is unclear.The aim of this study was to investigate the effect of HDL-C in young male patients.Methods:We recruited 267 consecutive young male patients (≤44 years) diagnosed with AMI.Other 247 participants free from coronary heart disease were enrolled as controls.HDL-C levels of AMI patients and controls were evaluated to analyze the predictive value on AMI.According to the cutoff point of 1.04 mmol/L HDL-C,patients of AMI were divided into two subgroups (normal HDL-C group and low HDL-C group) and were followed up for 2 years.Clinical end points included all major adverse coronary events (MACEs):the main cause of death,nonfatal myocardial infarction,readmissions for acute coronary syndrome,arrhythmias,or revascularization.The prognostic value of HDL-C was evaluated using Cox regression according to MACE.Results:Patients of AMI had decreased proportion in normal HDL-C group compared to controls (47.2％ vs.57.9％;P =0.017).Logistic regression analysis showed that there was an inverse relationship between HDL-C and AMI in young males.In the low HDL-C subgroup of AMI patients (n =14l),34 (24.1％) patients experienced a MACE during the 2-year follow-up,compared with 15 (11.9％) patients in normal HDL-C subgroup (n =126).The Cox regression analysis showed that HDL-C was an independent predictor of a MACE during the follow-up period (hazard ratio =0.354,P =0.006).Conclusion:HDL-C was an important parameter for predicting the risk and the clinical outcomes of AMI in young male patients.