A high level of the spread of coronavirus (CV) infection among hamadryas baboons and macaques of different species (about 50%), both resident in the animal house and imported, has been established. The tropism of CV to the gastrointestinal and respiratory tracts has been demonstrated. The course of spontaneous CV infection is accompanied by enterocolitis and/or pneumonia with periodic exacerbations, or takes the inapparent form. Cases of virus persistence have also been noted. Infected macaques exhibited an increase in the titers of antibodies to their own CV strain isolated from these animals, as well as to antigenically related human CV strain 0043. Spontaneous CV infection in monkeys may be used for solving some obscure problems of the pathogenesis and epidemiology of CV infection in humans.