Aim To study the association between insertion/deletion polymorphism of angiotensin converting enzyme gene and coronary artery disease.Methods The insertion/deletion of a 287 base pairs segment in 16 intron of angiotensin converting enzyme gene in 79 coronary artery disease patients and 68 healthy subjects was detected by polymerase chain reaction. The subjects were divided into three groups:homozygotes for the deletion, homozygotes for the insertion and heterozygotes, according to its presence orabsence. The serum angiotensin converting enzyme activity was also detected.Results The deletion genotype frequency in coronary artery disease group was marked higher than in controls (p<0.05). The frequency of deletion allele was also greater than that in controls (p<0. 05).The serum angiotensin converting enzyrne activity between coronary artery disease patients and controls was similar. But it was significantly different among different genotypes in two groups. The deletion genotype had the highest, insertion genotype had the lowest.Conclusion The insertion/deletion polymorphism of angiotensin converting enzyme gene is associated with coronary artery disease, and the deletion genotype perhaps is a risk factor for coronary artery diseaes. The elevated serum angiotensin converting enzyme level may contribute to the generation of coronary artery disease in patients who have deletion genotype.