The chromosomal localization of the chicken transferrin receptor gene, as well as sequences that were homologous to the viral oncogene v-fos and the human gene families ZFY and SRY were determined by the method of nonisotopic DNA-DNA in situ hybridization. A correspondence was revealed between the Comptonian linkage group 10 and chromosome 1. A common origin of avian chromosome Z and mammalian chromosome Y is hypothesized.