The correlation between the level of chromosomal aberrations and CYP1A genotypes in adolescents of the Tashtagol boarding school (Kemerovo region) exposed to a combined effect of high doses of radon and heavy metals has been studied. It was found that the level of chromosomal aberrations shows a statistically significantly increase in carriers of at least one CYP1A1*2A (A2455G) allele. The frequency of ring chromosomes shows a statistically significant increase in carriers of the CYP1A1 *1A*1A (T3801C) genotype. The frequency of multiple chromosomal aberrations was higher in carriers of the CYP1A2*1A*1A genotype. A conclusion on the important role of polymorphic CYP1A loci in genotoxic effects of radon and heavy metals is made.