The book is the result of summarization of data from the author's dissertation and the joint research work with colleagues on studying genetic peculiarities of 27 Russian horse breeds at microsatellite loci. The private alleles were registered in some native breeds including Altai, Bashkir, Kabardian, Mezen, Pechora, Vyatka and Yakut. Native breeds of horses have a relatively high level of interbreed differentiation, indicating the need of studying multiple subpopulations to complete information about the breed. The author expresses the hope that the book will be useful for wide circles of specialists and readers interested in genetics of horse breeds.