A hot saline antigen from Brucella ovis REO 198 was extracted to be used in an indirect ELISA test (ELISA-I) for the diagnosis of sheep brucellosis. This antigen was comparatively used in the ELISA-I and Gel Immune Diffusion test (IDG) in 1181 serum samples belonging to sheep of different epidemiological statuses. The extracted antigen was highly hydrophilic performing the tests easily. The better relative sensitivity showed by the ELISA-I over IDG is discussed.