Abstract: AIM: To investigate clinical, angiographic and biochemical features in Chinese patients with early-onset coronary heart disease (CHD). METHODS: Ninety-five consecutive patients with clinical onset of CHD at age ≤45 years, 252 patients with clinical onset of the disease at ≥55 years and 54 age-matched healthy subjects were included in the study. All patients had documented CHD according to angiography. Angiographic features, as well as clinical and biochemical risk factors, were compared between groups. RESULTS: Compared with the prevalence in healthy subjects, a higher prevalence in hypertension, diabetes, smoking history and family history of CHD was found in early-onset CHD patients. Patients ≤45 years of age had lower high-density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apoA-I) levels but higher triglyceride, lipoprotein(α) and high-sensitivity C-reactive protein (hsCRP) levels. Early-onset CHD showed a higher incidence of myocardial infarction and preponderance of one-vessel disease, but there were no significant differences in Gensini scores. CONCLUSION: Hypertension, diabetes, smoking, family history of CHD, high plasma triglyceride, low HDL-C levels and apoA-I are associated with early-onset CHD. The reduction of HDL-C and apoA-I may be the most important lipid risk factor in the development of early-onset CHD.