In an expenment, the study of effect of Embryo Transfer (E.T) and Natural Service (N.S) on the humoral immune response in Finn and Rahmani sheep vaccinated by inactivated RVF-vaccine was determined by Complement-Fixation test(CFT).  Generaly, the level of humoral antibodies of RVF-vaccine was higher in pregnant Finn breed than the local Rahmani breed either in (E.T) or in (N.S), ie. (ET) was associated with a higher Ievel of antibodies than (N.S) in two breeds. Also, Finn bora lambs had 2 higher level of RVF maternal antibodies than Rahmani born lambs, whether, by (ET) or by (N.S).