Abstract: Objective To study the relationship between HSP70 polymorphisms and susceptibility to hypertension in workers exposed to heat stress.Methods Totally 158 steel workers and rollers were selected as the exposure group and 76 workers without heat stress exposure were selected as the control group.The general status and the blood pressure were investigated.HSP70 genotypes were analyzed by using polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP)technique and the haplotype was caluclated with PHASE 2.0 software.Results HSP70 genotype frequencies of the exposure and the non-exposure groups were not significantly different in the workers with normal blood pressure or hypertension.HSP70-1 C/C genotype frequency in the workers with higher blood pressure was significantly higher than those in heat-unexposed workers with hypertension(P<0.05).Compared with G/G genotype,C/C genotype was a risk factor for increased blood pressure,with an adjusted odds ratioORof 3.52(95% confidence intervalCI:1.02-12.11)for all workers.HSP70-2 G/G genotype frequency in the workers with higher blood pressure in exposure group was significantly higher than that of workers with hypertension or normal blood pressure in unexposure group(P<0.05).HSP70-2 G/A genotype frequency in the workers with higher blood pressure in exposure group was significantly lower than that in wokders with hypertension or normal blood pressure in unexposure group(P<0.05).The results of multiple logistic regression analyses showed that G/A genotype in exposure group was a protective factor for increased blood pressure with an adjusted OR of 0.25(95% CI:0.08-0.78)and GAT/*** haplotype pairs were risk factors for hypertension of exposure groups,with an adjustment OR value of 1.29(95% CI:1.02-12.44).Conclusion HSP70-1 C/C genotypes are associated with increased blood pressure in the workdrs.HSP70-2 G/G genotypes are associated with increased blood pressure in workers exposed to heat stress.G/A genotype is a protective factor for increased blood pressure.GAT/＊＊＊haplotype pairs are associated with hypertension susceptibility in workers exposed to heat stress.