objective:to evaluate the effects of tlr3 single nucleotide polymorphisms (snps) on asthma risk and asthma－related phenotypes in a southeastern chinese han population. Methods:rs3775291,a nonsynonymous snp which was located in the fourth exon of tlr3,was selected. Three hundred and eighteen unrelated adult asthmatic patients and 352 healthy volunteers from the same area of southeast china were recruited in this study. Genotyping of the selected snp was performed using multiplex pcr in conjunction with tagged array single base extension technology. We conducted case－control association studies between the selected snp in tlr3 and asthma or asthma－related phenotypes. Results:rs3775291 snps was not associated with asthma morbid risk in whole. However,ga+aa genotypes had a significant reduced risk of atopic asthma by 31% (adjusted or= 0.69,95%ci = 0.49~0.97),which showed an independent role. The carriers of ga/aa genotype appeared less nocturnal asthma symptom compared with those of gg genotype. No correlation was found between the snp and eosinophil counts,total serum ige levels or asthma severity. Conclusion:tlr3 polymorphisms may play a considerable role in the pathogenesis of atopic asthma. It could be clinically useful both for identifying patients at risk of asthma and for preventing its occurrence.