In this study, a total of 250 bovine and 250 ovine-caprine sera were tested for anli-Brucella antibodies with Rose Bengal plate test (RBPT), serum agglutination test (SAT) and Coombs (anti-globulin test-AGT) test. Among 250 bovine sera, 150 were obtained from an infected herd. Serological examination of the cattle sera revealed 98 (65.3%) RBPT-positive and 52 (34.7%) RBPT-negative results for the infected group, and 20 (20.0%) RBPT-positive and 80 (80.0%) RBPT-negative results for the suspect group, while in SAT 85 (56.7%), 27 (18.0%) and 38 (25.3%) sera from the infected group, and 44 (44.0%), 6 (6.0%) and 50 (50.0%) sera from the suspect group were evaluated as positive, inconclusive and negative, respectively. Among 250 ovine-caprine sera 94 (37.6%) RBPT-positive and 156 (62.4%) RBPT-negative results were observed, while 111 (44.4%), 84 (33.6%) and 55 (22.0%) of them were regarded as positive, inconclusive and negative in SAT, respectively. Two to five-fold enhancements in average were observed in titreş of overall SAT-positive bovine (44/129, 34.1%), and ovine-caprine (25/111, 22.5%) sera in Coombs test. Less pronounced enhancements in titreş of overall SAT-suspicious or -negative bovine (29/121, 23.9%), and ovine-caprine (16/139, 11,5%) sera were also detected in Coombs test. However, the anti-globulin enhancement in infected cattle was much more pronounced than the enhancement in non-infected animals. It was concluded that, the use of Coombs (anti-globulin) test, which detects the presence of incomplete or blocking antibodies in serum samples, together with RBPT and SAT in the serological diagnosis of bovine, ovine and caprine brucellosis would be useful, especially if the vaccination status of the animal is unknown.