To increase the sensitivity and reliability of immunodiagnostic assay for direct detection of chlamydial genital infection, we developed monoclonal antibodies (MAbs) that recognize the major outer membrane protein (MOMP) of all serovars of Chlamydia trachomatis. ELISA and dot-ELISA were used to select hybridomas that produced anti-C. trachomatis MAbs. Four MAb clones--A12.6, B serogroup specific; C1.5, C serogroup specific; G10.2, species specific; and E9.1, genus specific--were characterized by SDS-PAGE and immunoblot and were reactive with MOMP of C. trachomatis. The species-specific MAb G10.2 had a molecular mass of 40 kDa. The reactivity of developed species-specific monoclonal antibody for detection of C. trachomatis antigen in endocervical specimens was compared with the commercially available DFA test. We found that developed antibody had high sensitivity (97.22%) compared to DFA for detection of chlamydial infection in endocervical samples. It can be used as a reliable method in laboratories for the diagnosis of chlamydial infections.