Authors investigated the frequency of genital chlamydial infection. 83 couples--complaining with infertility--were examined. Twenty patients were chlamydia positive by direct IF antigen detection. All chlamydia positive patients have elevated IgG antibody levels in sera. In 33 cases (18.1%) the antibody titers were significantly high above 1:128, in 58 cases (34.9%) antibody levels were slightly elevated between 1:16-1:64. Authors are analysing the questions of the humoral immune reactions and the results of the medical treatment.