Pseudomonas syringae bacteria were isolated and identified from the sugar beet leaves with the characteristics of destruction. Their biological properties were determined and compared with collection strains of phytopathogenic bacteria that cause bacterial disease of this culture. The isolated strains caused the necrotic dark spot formation on the leaves upon artificial inoculation of sugar beet plants, which gradually increased in size, while the tissues inside of the spots got dry and fell out. We demonstrated that the lipids of bacteria cells, isolated from infected leaves of sugar beet, include fatty acids, which are typical for Pseudomonas syringae according to quantitative and qualitative composition. The studied strains showed serological relationship with antiserum against strains- pathovars P. syringae of various serogroups. The high titer of the investigated strains in agglutination reaction with antiserums against representatives of IV serogroup indicates their affiliation to the serogroup IV.