To study pathogenetic features of chronic joint pain, we examined 183 patients with rheumatoid arthritis (RA) and 80 patients with osteoarthrosis (OA). The presence of mixed pain syndrome was found. A neuropathic component of pain (NCP) was observed in some patients with nociceptive pain (43 and 30% with RA and OA, respectively). Patients with RA had tunnel syndromes (14%), polyneuropathies (55%), mononeuropathies (19%) and sensitive specific disorders, characteristic of NCP, which were localized in anatomic zones corresponding to affected nerves. No signs of the damage of the somatosensory nervous system were found in patients with OA. Neuropathic pain was concomitant to secondary hyperalgesia which covered the zones localized far from the affected joint that allowed to suggest the involvement of dysfunctional mechanisms in the pathogenesis of chronic pain in OA. The study opens new possibilities for pharmacotherapy.