The present study was aimed to evaluate the live mutagenized RVF-MP12 vaccine in 4 months old calves. The used dose was 5 log10 TCID5Janimal. The safety and potency of the vaccine was followed up as well as the duration of the immunity by ELISA and SNT through 12 months post vaccination. There was no evidence of untoward effects except slight elevation of body temperature in the calves through 14 days post vaccination. The virus was recovered from the sera of 3 calves on the 2nd  and 4th day post vaccination respectively 82,78 and 76, but there was no evidence to virus shedding in ocular, nasal nor rectal swabs. The immunity was detected as early as 7 days post vaccination to reach its peak by the 6th  month and still in a protective level only 10th  month post vaccination.