Canine distemper virus (CDV) has been reported worldwide in wild carnivores and has been cited as the cause of population declines in some species. Crab-eating foxes (Cerdocyon thous) from El Palmar National Park, Argentina, were observed either dead or exhibiting clinical neurologic signs. Samples were taken from two individuals that were later found to be positivefor CDV by direct immunofluorescence in brain tissue. Based on molecular studies, the CDV strain had a highpercentage of identity compared to CDV strains affecting dogs in Argentina.Thisis the first report of CDV infection in wild carnivores in Argentina.