An epizootic of malignant catarrhal fever (MCF) occurred at the Los Angeles Zoological Park which resulted in the deaths of four exotic ungulates. The source of infection was considered to be a newly purchased wildebeest bull (Connochaetes taurinus taurinus) that had been negative for antibody to MCF virus by an indirect immunofluorescent test. The need to re-evaluate regulations for the transportation and housing of young wildebeest is emphasized by this MCF outbreak. The diagnostic technology now available for identifying asymptomatic carriers of MCF virus and the present understanding of the behavior and pathogenesis of this highly cell-associated herpesvirus in exotic ruminants should provide a basis for the prevention and control of MCF in zoological parks.