Aim To study the apolipoprotein E(apo E) gene polymorphism relating to the severity of coronary artery disease(CAD) and its impact on prognosis. Methods Polymerase chain reaction-restriction fragment length(PCR-RFLP) was used to determine apoE genotype of 251 CAD patients and 200 controls.Plasma lipid levels were measured by routine ways. Results Five kinds of apoE genotype,ε3/3,ε3/2,ε4/3,ε4/2 and ε4/4 were detected in the study.It indicates that different kind of apo E allele had different function on plasma lipid and lipoprotein levels.There were statistic differences in apoE ε4/3 genotype and ε4 allele frequencies between normal-lipid-leveled CAD patients and controls,but between the two hyperlipidemia subgroups,no differences had been found.Patients with heart function of class Ⅲ~Ⅳ had higher apoE ε4/3 genotype and ε4 allele frequencis and lower ε3/3 genotype frequencies than those with better heart function(class Ⅰ~Ⅱ). Conclusion Apo E gene polymorphism is involved in the occurrence,the development and the heart of CAD.ApoE ε4/3 genotype and ε4 allele are important genetic fators of CAD and may have relationship with worse heart function or cardiac events,while ε3/3 genotype might be a protective factor of CAD.