Background. With continuing automatization it comes into consideration, which tests should be a part of the syphilis screening. Trying to learn more about the correlation and comparability of passive hemaglutination and imunoenzymatic assay, which are the candidate reactions on the screening test, we analyzed results of the above mentioned reactions in 2319 serum samples sent for diagnostics of syphilis. Special attention was paid to sera with contradictory results in both tests. Methods and Results. When results were contradictory the patient’s probability of having syphilis and the intensity of the reaction were analysed. Out of 2319 sera samples examined for syphilis 141 (6.1 %) specimens belonging to 125 patients were found to provide contradictory results in passive hemagglutination (TPHA) and immunoenzymatic assay for the specific imunoglobulins G (ELISA IgG). In 14 cases (children of syphilitic mothers) only the passively transferred antibodies were found and these samples were excluded from the examined group. Almost four fifths of contradictions (88 out of 111, i.e. 79.3 %) were based on the positivity of TPHA with the negativity of ELISA IgG and one fifth only (23 specimens, i.e. 20.3 %) concerned the positivity of ELISA IgG with the negativity of TPHA. The relation to syphilis was more obvious in the TPHA-positive patients: in 88 TPHA-positive patients the syphilitics were relatively more common (39 syphilitics, i.e. 44.3 %) than in 23 ELISA-positive patients (5 syphilitics, i.e. 21.7 %), the difference is statistically significant (p<0.05). Conclusions. It is concluded that TPHA seems to be more sensitive, whereas ELISA IgG more specific.

        Key words: syphilis, serodiagnostic, passive hemagglutination, ELISA, contradictory results.