The variability of Q-heterochromatin regions (Q-HR) was studied in native residents of the northern part of West Siberia, viz Yakuts (n = 127), Selkups (n = 90) and Khants (n = 54), as well as in newcomers including oil-borers (n = 43) and children (n = 113) living permanently in this part of the USSR. The major quantitative characteristics of chromosomal Q-HR variability were shown to be very similar in oil-borers and natives, and this is considered to be the result of specific selection of individuals according to the amount of Q-HRs in their genome. The hypothesis on the possible selective value of chromosomal Q-HRs in human adaptation to extreme environmental conditions of the extreme north is discussed.