Three serological assays were evaluated for the diagnosis of brucellosis in sheep: the Rose Bengal plate test as a screening test (RBPT), agar gel immunodiffusion with Native Hapten test (AGID-NH) and an indirect enzyme-linked immunosorbent assay (iELISA). For optimal sensitivity, RBPT had to be used with sera: antigen at a 3:1 dilution. With the sera from B. melitensis culture-positive sheep, the sensitivity was 100% for RBPT, and iELISA; while, it was 93.8% for AGID-NH test. On the other hand specificity was 100% when testing the sera from 145 brucella-free sheep. Larger discrepancies among the results of the serological tests were obtained with sera from sheep of areas where brucellosis is endemic. Sheep vaccinated with B. melitensis Rev.1 subcutaneously and conjunctively showed negative result in all tests after twelve and six months respectively. The proportion of sheep giving a positive reaction after vaccination decreased faster in AGID-NH test than in other tests. The using of RBPT or ELISA with combination with AGID-NH is the best choice for diagnosis of infected and vaccinated sheep.