An epidemiological study was carried out to determine the seroprevalence of Chlamydia abortus (C. abortus) in sheep in Bosnia and Herzegovina. This was the first systematic study of this kind carried out in Bosnia and Herzegovina. Samples were collected during 2012 and 19 sheep flocks, located in the different parts of the country and with a recorded history of reproductive failures (abortion, stillbirths and infertility) were involved. A representative sample from each flock was taken by a simple random sampling allowing the detection of seropositive animals within a flock with 95% confidence, with expected prevalence rates of 20%, using the recommendations for determining the required necessary sample size to detect the presence of disease. In total 178 sheep blood sera were tested for the specific antibodies against C. abortus, with the use of enzyme-linked immunosorbent assay (CHEKIT* Chlamydophila abortus Antibody Test Kit). The results showed that 77 (43.3%) out of 178 ovine sera were seropositive for C. abortus infection, as indicated by the manufacturer's interpretation of the results. The flock was considered to be positive if at least one animal was seropositive. The flock prevalence of C. abortus in the examined flocks was 84.2% (16/19 flocks). The results of the present study indicate that C. abortus infection occurs frequently in sheep in Bosnia and Herzegovina. Key words: Bosnia and Herzegovina, Chlamydia abortus, seroprevalence, sheep U radu je opisano epidemiolosko istrazivanje s ciljem utvrdivanja seroprevalencije protutijela za vrstu Chlamydia abortus ovaca u Bosni i Hercegovini (BiH). Ovo je prvo sustavno istrazivanje ove vrste provedeno u BiH. Uzorci seruma bili su uzeti tijekom 2012. godine, a bilo je obuhvaceno 19 stada ovaca s registriranim reprodukcijskim poremecajima (pobacaji, mrtvorodenja, neplodnost) diljem drzave. Reprezentativan uzorak iz svakog stada osigurali smo jednostavnim slucajnim odabirom kojim je omoguceno otkrivanje seropozitivnosti unutar stada na 95%-tnoj razini povjerljivosti, s ocekivanom prevalencijom od 20%, sluzeci se preporukama za odredivanje potrebne velicine uzorka za otkrivanje prisutnosti bolesti. Pretrazeno je ukupno 178 uzoraka krvnog seruma ovaca na prisutnost specificnih protutijela protiv C. abortus pomocu imunoenzimnog testa (CHEKIT* Chlamydophila abortus Antibody Test Kit). Sukladno preporukama proizvodaca za tumacenje rezultata, od ukupno 178 pretrazenih uzoraka 77 (43,3%) je bilo pozitivno na C. abortus. Stado se smatralo pozitivnim ako je sadrzavalo makar jednu seropozitivnu ivotinju. Prevalencija obuhvacenih stada na C. abortus iznosila je 84,2% (16/19 stada). Rezultati ovog istrazivanja ukazuju na cinjenicu da je infekcija vrstom C. abortus kod ovaca u Bosni i Hercegovini vrlo prosirena. Kljucne rijeci: Bosna i Hercegovina, Chlamydia abortus, seroprevalencija, ovce