The three-hour immobilizational stress in two groups of males of rhesus monkeys at the age of 7-8 and 10-12 years has been investigated. The reaction on the stress has been established to depend on the age of animals. The young males bear the stress easier, their behaviour after it is practically normal. The normal behaviour of the elder animals restores during 24 hours after immobilization. A comparative analysis of hamadryas baboons and rhesus monkeys behaviour during this type of stress has been carried out. These species differ by their reaction on stress: Papio hamadryas serve as a model of hard depressive stress, the rhesus monkeys--a model of slight-stimulative stress. The peculiarities of stress bearing depend on the selected species, age of the animal, the type of social organization and individual features of behaviour.