Aim To study the relationship between serum bilirubin levels and coronary artery disease.Methods 120 patients undergoing diagnostic coronary arteriography(CAG) were divided into two groups:the control group(the results of CAG is normal) with 40 patients,the coronary heart disease group(≥50% diameter narrowing) with 80 patients.15 cases of coronary heart disease group were mild,32 cases of coronary heart disease group were moderate and 33 cases of coronary heart disease group were severe.The serum bilirubin was determined with Malloy-Evelyn.Results Serum Level of bilirubin in coronary heart disease group were statistical significantly compared with control group(p<0.05).There was positive correlation between the serum level of bilirubin and the degree of coronary aretry narrowing(r=-0.26,p<0.05).Conclusions Low serum level of bilirubin may be a new dangerous factor for coronary heart disease.There is correlation between serum level of bilirubin and the degree of coronary aretry narrowing.