The results of chromosomal aberration level and spectrum study in 48-hours peripheral blood lymphocytes cultures of 10-19 years old children-teenagers (n = 132, mean 14.2 +/- 0.16 years old) living in the south part of Kemerovskaya area Gornaya Shoria are presented. Mean metaphases with aberrations were 4.74 +/- 0.21% in studied group that is significantly higher (p < 0.01) than background level of this index in this region (Kemerovskaya area)- 2.62 +/- 0.29%. Aberrations frequencies of separate classes were 2.83 +/- 0.16 for single fragments; 1.89 +/- 0.14 for pair fragments; 0.05 +/- 0.02 for chromatide exchanges and 0.32 +/- 0.05 for chromosome type exchanges. Furthermore in 6 individuals (4.55%) were found Rogue cells that were contained polycentric, ring chromosomes and multiple pair dot fragments. The reasons of chromosomal aberrations frequency increasing in this mountain area inhabitants are discussed (ultrahigh radon radiation doses influence are included).