Articular lesions in 157 patients infected with ixodes tick-borne borreliosis (ITB) in a central Russia's region set on, on the average, in 4 months after tick attack; they were associated with systemic signs of an early disseminated infection and set on less seldom in a late period. The most often encountered systemic signs were as follows: secondary erythema (32% of patients), neurological syndrome (13%), cardio-vascular lesions (22%), ocular lesions (13%) and hepatic lesions (8%). The articular syndrome manifested itself through arthralgia (53 patients) and arthritis (104 patients), which set on quite often in the tick-attack area. There was a peculiarity typical of articular lesions, which made it possible to distinguish them from other rheumatic disease. A dynamic follow-up revealed different clinical variations of Lyme's arthritis and peculiarities of the genetic profile, i.e. a higher prevalence of HLA A2, HLA-B15 and HLA-DR4 as well as of haplo-types HLA A2-B15 and HLAB15-DR4. The articular lesions were associated with an intensive specific humoral immune response. The instrumental examination methods, i.e. ultrasonography of joints as well as scintigraphy of bones and joints, did not reveal any qualitative differences between arthralgia and arthritis, which is indicative of a common nature different-intensity manifestations of arthropathy in thick-borne borreliosis.