In this study, a trial to improve the alteady produced inactivated RVF vaccine. This vaccine was inactivated by using ultra-violet rays. The results obtained in the present investigation could be indicated the optimum time for inactivation of RVF virus using ultra violet. It is clear that ultraviolet completely inactivated RVF virus particles after 20 minutes from exposure with no residual infective virus, meaning a much more Safe and potent vaccine. The immune response of this vaccine has been tested by vaccinating susceptible sheep and in seroconverted these animals by carrying serum neutralization test. Neutralizing antibodies were detected at the first Week post vaccination with an index of 0.8. Then it reached a level of 2.5 by the 4th week post vaccination. When these vaccinated animals were challenged with virulent RVFV, the animals did not reveal any thermal reaction. On the contrary, the non vaccinated challenged control revealed high thermal reaction. From these results, we can conclude that ultra-violet inactivated vaccine was a safe and potent vaccine as well as adequately immunogenic and efficient for vaccination of susceptible animals as it induced a good immune response when measuring the humeral immune response.