The nucleoprotein of Borna disease virus (BDV-p40) was produced in a Baculovirus expression system using sf9 cells. The purity and specificity of the recombinant p40 was confirmed by SDS-PAGE and immunoblotting. The recombinant p40 was used in an ELISA to screen horse sera in Turkey. For this, 323 horses from selected cities in the Marmara region of Turkey were examined clinically and serum was collected from each. All horses were clinically healthy except for a few with wounds on the skin. Antibodies to BDV were detected in the sera of 82 (25%) of 323 horse sera. Six sera were selected that had low, medium or high OD values by ELISA and were analysed by Western blotting. All reacted specifically with p40 at a dilution of 1 in 1000. This is the first report of the detection of Borna disease in Turkey and needs further molecular biological investigations to compare the Turkish strains with those strains detected in Europe.