The study of the rate of occurrence of hepatitis A (HA) markers among monkeys, both newly arriving and those born and living for long periods (aboriginals) in the Sukhumi farm, was carried out. The rate of detection of antibody to HAV (anti-HAV) was shown to vary from 47% (Papio hamadryas) to 100% (Macaca arctoides and Macaca fascicularis). The level of infection with HAV varied among different groups of the same species: Macaca rhesus from 30% to 96%, Papio hamadryas from 0 to 82%. During a long-term observation period seroconversion to HAV was observed in monkeys arriving to the farm from natural habitats. In M. rhesus upon arrival the anti-HAV were detected in 7% and by the end of the observation period reached 100%, in green monkeys 28% and 92%, respectively. Anti-HAV of the IgM class were detected in animals with seroconversion. In fecal extracts from M. rhesus and in the liver, feces, and intestinal contents of green monkeys HAV was found cross-reacting with simian and human sera containing anti-HAV. The virions isolated from a green monkey liver had a buoyant density in CsCl 1.36 g/cm3, and HAV from feces of a M. rhesus sedimented in the density zone of 1.34 g/cm3.