Numerous research works indicate that staying in a hyperbaric environment is a stressor. We have undertaken studies using an animal model to determine the effect of hyperbaria on adrenocortical secretion and the level of adrenal ascorbic acid (a.a.a.). The research was conducted on 70 male hooded rats, which were divided into groups and subjected to hyperbaric air and oxygen at an overpressure of 1 and 3 atn, with some of the animals being additionally burdened with physical effort (swimming). It was found that short-term exposures (30 minutes) of rats to hyperbaric conditions caused a decrease in the content of a.a.a. With a prolonged (3-hour) exposure to 3 atm air the a.a.a. content returns to a normal level. A reduction in the a.a.a. content indicates the presence of stress in hyperbaric conditions in the rat, however, it does not allow to determine its intensity with the method used in the study.