In this paper, we analyzed the distribution and the transcriptional activity of different repetitive elements in the sex chromosomes of chicken at the lampbrush stage. Based on these results, we suggest participation of interspersed repeats in the maintenance evolutionarily significant level of variability of heteromorphic sex chromosomes in birds. Analysis of the organization peculiarities of chicken sex chromosome W specific repeats allowed us to hypothesize that the accumulation of tandem repeats enriched with homopurine tracks is significant for the evolution of sex chromosomes.