Abstract: Objective To investigate the association between CASP3 and CASP7 gene polymorphism and the susceptibility of noise-induced hearing loss (NIHL) in a Chinese Han occupation population.Methods A 1:1 case-control study was conducted among 272 cases with high frequency hearing threshold of >25 decibels(dB)and 272 gender-,age-,years of noise exposure-,and workplace-matched controls with the threshold of ≦25dB selected from a total of 1 549 noise-exposed workers in Hangzhou city.The genotypes of CASP3 rs1049216 and CASP7 rs10787498 were determined with polymerase chain reaction-ligase detection reaction(PCR-LDR).The associations of genetic variations of CASP3 and CASP7 with NIHL were assessed by using multivariate logistic regression,and dichotomy analysis was used to evaluate the interaction between environmental risk factors and gene polymorphism on HIHL.Results There was no statistical difference in the frequency of alleles and genotypes of CASP7 rs10787498 between cases and controls.But genetic variation of CASP3 rs1049216 was associated with NIHL;the subjects with mutant allele (CT or TT) of CASP3 rs1049216 showed a decreased NIHL risk (adjusted odds ratio OR=0.65,95% confidence interval 95%CI:0.43-0.97).The results of dichotomy analysis revealed interactions between genotype of CASP3 rs1049216 and environment risk factors including education level and sleeping time.Conclusion There is a correlation between CASP3 rs1049216 mutation and the susceptibility of NIHL and there are interactions between the influences of CASP3 rs1049216 polymorphism and educational level and sleeping time on the susceptibility of NIHL in Chinese Han workers.