Berrimah (BRH) virus is a rhabdovirus closely related antigenically to bovine ephemeral fever (BEF) virus. Two cows were given two doses of purified BRH virus with Qui! A adjuvant, 22 days apart. There was no clinical reaction and a minimal skin reaction. They were challenged with virulent BEF virus, 6 days after the second dose and did not show a cUnical reaction or experience a viraemia. in contrast to the controls one of which had been sham vaccinated with tissue culture cells. Both vaccinates developed antibodies to BRH and BEF viruses as measured by an ELISA test to BEF virus and virus neutralisation tests to BRH and BEF viruses. This experiment demonstrates that cross protection occurs when BRH infection precedes BEF virus infection in contrast to pre-infection with Kimberley infection which is non- protective.