A serological study was carried out on 6495, 8457 and 3872 sera of cattle, sheep and goats in five different localites in Assiut Governorate (Dirout, El-Kossia, Manflout, Sedfa and Assiut center) to estimate the incidence of brucella infection among some ruminant animals (cattle, sheep and goats) in Assiut Governorate through the period from November 1997 to December 1998. All samples were serologically examined by Rose Bengal plate test (RBPT), Buffer Acidified Plate test (BAPAT) and positive sera were confirmed by tube agglutination test (TAT) and Rivanol test. The obtained results indicate that the incidence of brucellosis amog cattle, sheep and goats, in five different localities (Dirout, Manflout, El-kossia, Sedfa and Assiut) of Assiut Governorate in cattle, sheep and goats were (0.96 %, 0.48%, 0.36, 0.54 %, 0.47%), (1.1%, 1.8%, 1.04%, 0.8%, 0.0%), and (0.9%, 1.7%, 0.8%, 0.75%, 0.0%) respectively. The brucella seroprevalence proportion among cattle, sheep and goats in Assiut Governorate by different 4 serological tests (RBPT, BAPAT, TAT and Rivanol) were (0.61%, 0.61%, 0.46%, 0.58%,), (1.15%, 1.15%, 0.85%, 1.1%) and (1.1%, 1.1%, 0.74%, 1% respectively. Also it was found that RBAPT, BAPAT more efficient and highly sensitive in screening work and detection of brucella infection, on other hand TAT is a poor sensitive and specific, while Rivanol test is more specific and sensitive in comparison to other tests RBAPT, BAPAT and TAT).