Aim To study size of low density lipoprotein (LDL) particle in patients with coronary artery disease (CHD).Methods Plasma LDL in 37 CHD patients and 26 control subjects were analyzed by 2%～16% non-denaturing polyacrylamide gradient gels. Results The CHD patients had significantly less particle diameters than control subjects(25.71±0.66 nm vs. 26.41±0.95 nm, respectively;P<0.01). The distribution of LDL subfraction pattern was significantly difference between two groups (P<0.05). LDL particle diameter was found negatively correlated with plasma triglycerides (r=-0.29,P<0.05) and apoB (r=-0.25,P<0.05) level, while positively correlated with plasma HDLC level(r=0.28,P<0.05). Free cholesterol to protein ratio of LDL in pattern B was found less than that in pattern A (1.02±0.45 vs. 1.59±1.21,P<0.05), meanwhile a significantly positive correlation was also found between LDL particle diameter and this ratio (r=0.31,P<0.05).Conclusion Small, density pattern B LDL subfraction may be a risk factor for atherosclerosis. Plasma triglyceride may be a factor in regulation of LDL subfraction particle diameter.