Preparation of freeze-dried live attenuated IBR vaccine was used in emergency during outbreaks by nasal vacdnation. The evaluation of attenuated IBR vaccine in laboratory was conducted through studying purity, safety in laboratory animals and calves, potency in calves and duration of immunity. Twelve susceptible 6-9 months old calves free from antibodies against IBR virus were vaccinated Intranasaliy with a 2m1 dose containing 6.5 logo TCIDRidose. The immunogenic value of the vaccine was determined on the basis of the level of neutralizing antibodies in serum using serum neutralization (SNT). Rise in the level of specific antibody was dearly seen 2 or 3 weeks of vaccination and the EUSA was used to measure the level of antibodes, which came in harmony with those of SNT. Effectiveness of the vaccine was tested 8 weeks post-vaccination by challenging the calves with virulent strain of IBR virus. The results Indicate that the live attenuated vaccine was sufficiently immunogenic to stimulate the pa:dui:lion of di tibudim as_:whist IBR Infection.