Methods of differentiation and identification of Yersinia pestis strains of medieval biovar by real-time PCR method with hybridization-fluorescent results’ registration and SNP typing method have been developed. Ninety-one Y. pestis strains of medieval biovar from the plague foci of Russia and other CIS countries, received from the State Collection of Pathogenic Bacteria at the Russian Research Anti-Plague Institute “Microbe”, were used in this work. The strains of medieval biovar are represented by four already known phylogenetic lines: 2.MED0, 2.MED1, 2.MED2, 2.MED3.