Objective:To investigate the possible association between the C-1818T polymorphism in exon 4 of KLOTHO gene and acute coronary syndrome(ACS)in the Chinese Han population of Suwan region. Methods:A case-control study was conducted,including 375 patients with ACS(ACS group)and 235 control subjects who were free from coronary artery disease by coherence checks(control group). The KLOTHO gene C-1818T polymorphism was determined by polymerase chain reaction(PCR)and gene microarray. Results:Compared with the control group,① The frequencies of CC,CT,TT genotypes and the T allele of the C-1818T in ACS group were not significantly different;②The prevalence of the CT genotype is obviously higher in elderly patients(age≥60 years),male and also the elderly male with ACS(P value was 0.031,0.035,0.041 respectively). Furthermore,after adjustment for conventional risk factors, multiple logistic regression analysis showed that the CT genotype was a significant risk factor for ACS in the elderly or elderly male carrier(P values were 0.010 and 0.047 respectively),and no association with ACS in male(P=0.103). Conclusion:The CT genotype of KLOTHO gene C-1818T polymorphism was associated with the susceptibility to ACS in the elderly(age≥60 years),especially in elderly male in the Chinese Han population of Suwan region.