Coronary artery disease (CAD) is the most prevalent type of cardiovascular disease (CVD) which, according to the American Heart Association accounts for 35% of all deaths in U.S.A. Apolipoprotein E (ApoE) is an apoprotein found in the chylomicrons and IDLs that binds to a specific receptor on liver cells and peripheral cells and it is essential for the normal catabolism of triglyceride-rich lipoprotein constituents .This study was carried out on 35 subjects divided into two groups. First : 25 CAD patients, the patients ages were ranged between 43 to 71 years. Second : 10 control were normal, the control ages were ranged between 29-54 years. All the patients and control were selected from Cairo Medical Center, cardiology department. All subjects were submitted to the following: Full history taking. General clinical examination. Coronary angiography (tarnsfemoral catheterization). Laboratory investigation: Assessment of apolipoprotein E polymorphism by PCR and restriction enzymes. Measurement of serum cholesterol. Measurement of serum triacylglycerol. Measurement of serum low density lipoprotein cholesterol (LDLc). Measurement of serum high density lipoprotein cholesterol (HDLc). Measurement of serum cardiac enzymes and troponine.