Abstract：Toll-like receptor 4(TLR4) is one of the most important pattern recognition receptors(PRRs) in the Toll-like receptor family capable of sensing pathogen associated molecular patterns(PAMPs). The aim of this study was to investigate the single nucleotide polymorphisms(SNPs) of TLR4 and its association with immune traits in the laying ducks. The 2 254 bp sequence of exon 3 of TLR4 gene was analyzed with PCR-SBT method in Shaoxing laying ducks and Jiyun laying ducks(Anas platyrhyncha domestica). The results showed that 10 SNPs were detected. Among them, C433G was a silent mutation that did not induce the changes of amino acid, while other mutational loci were missense mutations. The result of Chi Square test indicated that the frequencies of 7 SNPs from the exon 3 of TLR4 gene fit with Hardy-Weinberg equilibrium in this population. The association between these genotypes with some important immune traits was analyzed with generalized least squares. The results showed that T141G and T398C were significantly associated with index of bursa of Fabricius and interleukin-2(IL-2) level (P＜0.05), and individuals with AB genotype had the highest all traits. A661G、T699C and A1563G were significantly associated with thymus index (P＜0.05 or P＜0.01). The results indicated that the 5 SNPs from the exon 3 of TLR4 gene are probable important molecular markers affecting immune traits，they can be candidate molecular markers for the laying duck breeding
