The paper gives the results of investigating chromosome aberrations in human peripheral blood lymphocytes due to DNA repair genes, such as hOGG1, ADPRT, APE1, XRCC1, XpG, XpC, XpD, and NBS1, upon long-term exposure to excess indoor radon concentrations. The frequency of chromosome aberrations was found to be significantly lower in the carriers of the genotype hOGG1 326 Ser/Ser (versus the variant Ser/Cys), APE1 148 Asp/Asp (versus Val/Ala and Ala/Ala). The study polymorphic systems were shown to be of value in giving rise to individual types of chromosome aberrations (single fragments and chromosome exchanges).