Our sex ratio analysis of mature individuals in populations of 5 lizard species, genus Eremias (Lacertidae) and genus Phrynocephalus (Agamidae), during the breeding season has shown that males predominate in the genus Eremias in most cases, while females predominate in the genus Phrynocephalus. This fact is confirmed by data collected by other researchers on 14 more species of the indicated genera. The authors believe that this difference is due to some ecological features of the noted systematic groups.