Objectives: To investigate 4 loci of 3 HSP70 genes in caustic soda production plant former workers, who have been exposed to metallic mercury vapors for a long time, and including numerous cases of chronic mercury intoxication (CMI). Material and Methods: Polymorphisms in HSP70 gene family members (HSP1A1 (+190G/C, rs1043618), HSPA1B (+1267A/G and +2074G/C, rs1061581) and HSP1AL (+2437T/C, rs2227956)) genes were studied among 120 male workers involved in caustic soda production by mercury electrolysis at 2 plants in Eastern Siberia. These subjects had been chronically exposed to metallic mercury vapors for > 5 years and divided into 3 groups based on the occurrence and time of the CMI diagnosis, or absence of this disease. The Group 1 consisted of individuals (N = 46), who had had contact with mercury but were not diagnosed with the CMI. The Group 2 included workers (N = 56), who were diagnosed with the CMI longer than 14 years ago. The Group 3 consisted of the subjects (N = 18), who had been diagnosed with the CMI 3–5 years ago. The logistic regression analysis was used for 3 genetic models with and without adjustment for age and duration of mercury vapor exposure. Results: We found that genotypes СС-HSPA1A (+190G/C) and GG-HSPA1B (+1267A/G) had a high predictive risk of the CMI development (adjusted odds ratio (OR_adj) = 5.58, p = 0.026 and OR_adj = 14.7, p = 0.0015, respectively). Twelve individuals with the CMI had a specific combination of СС-HSPA1A (+190G/C) and GG-HSPA1B (+1267A/G) genotypes, which strongly associated with the diagnosis (OR_adj = 12.3, p = 0.0285). Moreover, significant association with the CMI was also obtained for the haplotype G-C of 1267A/G and 190G/C polymorphisms (OR = 2.1, p = 0.018). Conclusions: The association of СС-HSPA1A (+190G/C) and GG-HSPA1B (+1267A/G) genotypes and their combination for the CMI individuals suggests the role for HSPA1 genes in mercury-dependent mechanisms of the CMI development and progression. Int J Occup Med Environ Health 2017;30(1):77–85