Previous studies indicated that in the Perm Region there are two pathogen species: B. garinii and B. afzelii which cause the disease mainly with neurological and dermatological manifestations. In 1990-1994, in the Perm Region 646 patients with Ixodes tick-borne borreliosis (ITBB), including 535 with erythema migrans, 54 without it, and 57 with late chronic disease were studied. Damages to the central and peripheral nervous systems were detected at all stages of an infectious process. The prevalent clinical manifestations are encephalitis, encephalomyeloradiculoneuropathies, mono- and polyneuropathies. These abnormalities are more frequently formed in patients with its erythema-free type both in the acute period of the disease and in the late period of infection. A varying spectrum of neurological syndromes and their significant incidence determine the resemblance of ITBB in Russia and West Europe. The clinical findings are in good agreement with the results of etiological structural studies of ITBB in the region.