In two epidemics of bovine ephemeral fever (BEF) in Egypt, one in 2000 and the other in 2001, the virus was probably carried by vectors transported by air currents across the neighboring countries and through red sea or across Suez Canal trough. Then carried by vectors, transported to neighboring Governorates, until reached Middle Egypt (Beni-Suef and El-Fayoum Governorates). The disease broke out under different ecological conditions among cattle and buffaloes populations and spread rapidly; it developed in spring and summer and ended in November. The morbidity rate in native breed cattle was 39.5%, 67.5% while it was 44%, 73% in foreign breed cattle and in buffaloes was 4.68%, 80% in Beni-suef and EL Fayoum Governorates respectively, at 2000 while it was 20.38%, 19.5% in native breed cattle, 30.38%, 43%; foreign breed and 5.9%, 6.6% in Buffaloes in Beni-suef and El- fayoum Governorates at 2001. Case fatality rate 1.5%, 2.16% in native breed cattle while it was 3.14% , 4.1% in foreign breed cattle in BEF outbreak at 2000 while it was 0.0% , 0.5% in native breed cattle and 2,2 in foreign breed cattle in EL – Fayoum and Beni-suef Governorates but buffaloes did no show any mortalities in either BEF outbreak at 2000 or 2001.The epidemic of BEF disease a 2001 was milder and shorter than that in 2000. All cattle and buffaloes affected in both outbreak were more than 3 month old. The vectors unknown certainly but the outbreaks occurred in summer sesion where that the possible vector mosquitoes and culicids species are evident.