The paper presents the results of investigating an association between the frequency of chromosome aberrations and the CYP1A1, CYP1A2*1F GSTM1, and GSTT1 genes involved in xenobiotic biotransformation in workers engaged in heat and power engineering. The group of workers is shown to have a significantly higher rate of metaphases with aberrations (4.03 +/- 0.17%; n = 231) than the control group (2.06 +/- 0.17%; n = 141). Cytogenetic disorders are not found to depend on gender, age, and length of service. The study indicated that the level of chromosome aberrations was significantly higher in carriers of the CTP1A1 C/C, GSTM1 0/0 and GSTT1 0/0 genotypes. In individuals with a combination of the GSTM1 0/0 and GSTT1 0/0 genotypes, the level of chromosome aberrations was ascertained to be significantly higher than that in those with the protective form of these genes.