The development of coronary atherosclerosis is associated with lipid oxidation and generation of free radicals. Several mechanisms have been attributed to anti atherogenic property of bilirubin. The first protective effect of bilirubin relates to the antioxidant property of bilirubin, which prevents lipid oxidation, especially low-density lipoprotein (LDL), and inhibits free radical-induced damages. Bilirubin has proven to be a potent antioxidant under physiological conditions by inhibiting lipid and protein oxidation. Hence based on above data the present study was planned for Assessment of Role of Serum Bilirubin in the Patients Diagnosed with Coronary Artery Disease. The present study was planned in Department of General Medicine, Indira Gandhi Institute of Medical sciences, Patna, Bihar. In the present study total 50 cases were enrolled. The 25 cases of the Coronary Artery Diseases were evaluated in Group A and remaining 25 control cases were evaluated in Group B. Total bilirubin level in the blood samples of all cases and controls were measured by diazo method (diazotized sulfanilic acid) and with colorimetric technique. The data generated from the present study concludes that there is an inverse association between serum bilirubin and risk of CAD. Higher serum bilirubin have protective role against CAD, even in the presence of other risk factor. Therefore, Bilirubin level can serve as predictive factor. If confirmed by future retrospective and prospective studies, bilirubin concentrations in conjunction with traditional risk factor could help identify those at high or low risk of CAD.