An enzyme-linked immunospecific assay (ELISA) for the serodiagnosis ofBrucella ovisinfection in sheep is described and compared with the cold complement fixation (CF) test. ELISA was performed in microtiter plates, using horse-radish peroxidase conjugated to anti-normal sheep serum globulins, and hydrogen peroxide pluso-phenylenediamine as substrate. A heated, cell-freeB. ovisextract was used as antigen in both tests.