On the basis of examining the changes of external respiration function and the central circulation in the course of treatment by hyperbaric oxygenation given to 64 patients with acute cerebral circulation disorders the authors have come to the following conclusions: a) patients with acute cerebral circulation disorders may show five types of the response to hyperbaric oxygenation; b) the type of the patient's response to each session may change during the treatment course; c) a prognosis of the response type is usually impossible; d) none of the response types leads to an aggravation of the disease clinical picture; e) the changed external respiration function and the central circulation return in 3 to 4 hours to their initial parameters.