Aim To study the clinical significance of low serum high density lipoprotein cholesterol (HDLC) levels in patients with coronary heart disease(CHD). Methods 224 patient with CHD were divided into acute myocardial infarction (AMI,n=90), unstable angina pectoris (UAP,n=78), stable angina pectoris (SAP,n=56) groups. Serum total cholesterol, triglyceride, HDLC levels were examined in 224 patients with CHD and in 50 healthy controls. Results There was no significant difference in serum total cholesterol levels between the CHD patient group (4.72±1.05 mmol/L) and healthy control group(4.78±0.72 mmol/L)(P>0.05), while serum HDLC level was significantly lower in CHD patient group (1.14±0.30 mmol/L) than healthy control group (1.45±0.26 mmol/L)(P<0.01). Serum HDLC level was significantly lower in AMI group than in UAP and SAP groups (P<0.01), when serum total cholesterol level was ≤ 5.16 mmol/L, serum HDLC levels were significantly lower not only in AMI group than in UAP and SAP groups (P<0.01), but also in UAP group than in SAP group (P<0.05). In CHD patients ,serum HDLC level was lower in smoking group (n=71) than in non-smoking group(n=57)(P<0.01). Conclusions Decrease of serum HDLC level is the most important lipid risk factor of CHD, especially in CHD patients with average or low average total serum cholesterol levels, and relates to the different CHD patterns.