Detection of DNA of Borrelia burgdorferi sensu lato was performed by PCR in taiga ticks Ixodes persulcatus, in blood samples and skin bioptates of small forest mammals, and in blood and urine samples of humans after attaching of ticks events. In Novosibirsk region both in natural reservoir and in patients with Ixodes ticks-borne borreliosis DNA of Borrelia garinii and Borrelia afzelii are detected. DNA of these borrelia were detected in 8 from 72 of taiga ticks, in 36 from 298 of blood and skin samples of small forest mammals, and in 32 from 102 of human blood and urine samples. In all studied samples DNA of B. garinii from NT29 subgroup was predominated. Borrelia DNA in which sequence of intergenic spacer region was homologous to sequence Chy13p first detected in China has been detected in one blood sample from red-backed vole (Clethrionomys rutilus).