Abstract： Objective To explore the association between Toll-like receptor 4(TLR4)gene polymorphism and nosoco-mial infection during lung cancer chemotherapy.Methods 209 patients with lung cancer who received chemotherapy treatment were selected as the research subjects.Sputum of the subjects was collected for pathogen detection,and the whole blood genome DNA was extracted using the kit.The product was amplified by PCR,and the gel imaging system was used to record the experi-mental results.The 2 polymorphic loci(rs4116652,rs4986790)of the amplified product TLR4 gene were sequenced and single nucleotide polymorphism typed,and combined with lung cancer chemotherapy Correlation analysis of concurrent nosocomial infec-tions during the period.Results In the infected group,the proportion of gram-positive bacteria infection was 39.02％,the pro-portion of gram-negative bacteria was 50.00％,the proportion of fungal infection was 6.10％,and the proportion of other patho-genic bacteria was 4.88％.The probability of gram-negative bacteria infection was The highest;the CC genotype distribution of the rs4116652 locus in the infected group and the uninfected group was significantly different from the C and G allele frequencies(P＜0.05).The CC genotype distribution and the G allele frequency in the infected group were high In the uninfected group,the frequency of C allele was lower than that of the uninfected group;the two groups of rs4986790 gene locus TT,TC genotype distri-bution and T,C allele frequency were significantly different(P＜0.05),the infected group The TT genotype distribution and T al-lele frequency were higher than those of the uninfected group,and the TC genotype distribution and C allele frequency were lower than those of the uninfected group.Conclusion TLR4 gene locus rs4116652,rs4986790 will increase the incidence of nosocomi-al infection during lung cancer chemotherapy,but this result needs to be further verified in a larger sample.