Objective To investigate the possible association of TLR4 polymorphisms with susceptibility and prognosis of SCAP.Method A total of 360 CAP patients hospitalized in emergency department of Zhongshan hospital from May 2005 to April 2008 were enrolled in this case-control study.Patients were excluded if they had metastatic tumors,autoimmune diseases,AIDS or received immunosuppressive drugs.This study was approved by the ethical committee of Zhongshan hospital,Fudan University.Patients were divided into SCAP group(n = 180)and NSCAP group(n = 180)according to the illness severity,and were divided into survival group(n = 300)and death group(n = 60)according to the 30-day mortality.Hapmap database of Han Chinese population was used to select the Tag SNPs.Primer 3 software was used to design the PCR and sequencing primers.Genomic DNA was extracted from peripheral blood mononuclear cells.Genotyping was performed by sequencing the PCR products.We used X2 analysis to evaluate the significance of differences in genotype and allele frequencies between different groups.Results The distributions of three TagSNPs(rs2149356,rs11536879,rs1927907)were consistent with Hardy-Weinberg equilibrium.The allele and genotype frequencies of three TagSNPs in the SCAP group did not differ from the NSCAP group.Also,no significant difference was found between survivor group and non-survivor group.The haplotype frequencies of CA,TA and TG were not significantly different between SCAP group and NSCAP group.And no significant difference of haplotype frequency was existed between survivor group and nonsurvivor group.Conclusions This study suggested that TLR4 gene polymorphisms were not significantly associated with the susceptibility and prognosis of SCAP.