Brucellosis and Rift valley fever are major diseases affecting sheep flocks where they cause substantial economic losses in sheep and goats flocks. This study was planned to experimental evaluation of simultaneous vaccination against Brucella and attenuated RVF (smith burn strain) diseases in sheep using serological test including SNT and ELISA test revealed that there was no antagonizing effect between the two vaccines on the immune response of vaccinated animals and the results showed that no significance differences in antibodies titer in all sheep groups which vaccinated either with Rev-I and attenuated RVF alone or simultaneously.