Urogenital chlamydial infection should act as a trigger of peripheral and axial form of arthritis like sexually acquired reactive arthritis and Reiter's syndrome assumedly. HLA B-27 positive patients with rheumatic disorders, mainly M. Bechterew (55 out of 62 men and 18 out of 25 women) were investigated for serum-IgG-antibodies to Chlamydia trachomatis (ELISA). Among HLA B-27 positive men and women urogenital disorders in their history were more common as compared with controls. There were found no differences concerning the rate of antichlamydial antibodies between patients and controls. It is supposed, that urogenital bacterial infections rather others than chlamydial infection may be connected with M. Bechterew.