Aim To observe the association between CXCL16 A181V polymorphism and the susceptiblity of acute coronary syndrome(ACS),furthermore,to approch the influence of CXCL16 A181V polymorphism to coronary severity in Xi'an Han population.Methods In the present study,we enrolled 183 patients with ACS and 88 patients without coronary artery disease(CAD).A181V polymorphism genotypes was determined by polymerase chain reaction-ligase detection reaction(PCR-LDR),and the coronary severity was counted with Gensini score.Results The comparative risk of ACS in AA homozygote was 4.053 times of VV homozygote,and the comparative risk of ACS in A allele carrier was 1.811 times to V carrier.The difference of Gensini score among A181 genotypes was significant(P=0.002).Conclusion A181V polymorphism is associated with susceptibility of ACS in Xi'an Han population,and also is associated with coronary severity.