A random specimen of 288 women was examined by the use of the indirect immunofluorescent test (IIF) for the proof of the Chlamydia trachomatis antigen in endocervical swabs (by the help of monoclonal antibodies), and with the ELISA test for the proof of IgG antibodies against Chlamydia trachomatis in serums, and the complement--fixation reaction for the proof of antibodies against the Chlamydia-group antigen. These women were previously examined anamnestically and clinically in detail. The Chlamydia trachomatis infection was determined in 29.51% of cases, with a high percentage of positive results in all age groups. These infections were more frequently proved, to a considerable extent, in women with the diagnosis of sterility than in all other examined women, and in relation to all other inflammatory processes it was most frequently diagnosed in women with uterine cervix changes (endocervicitis and erythroplasia). A high percentage of Chlamydia positive subjects (40.91%) was established in those examined women which had pathological pregnancies and births in their past medical histories. The humoral immune response to the presence of Chlamydia trachomatis infections was proven in 70.59% of cases. Presented and analyzed are the diagnostic possibilities of the used diagnostic tests, where the combination of the IIF and ELISA test has shown to be the best.(ABSTRACT TRUNCATED AT 250 WORDS)