To investigate the shifts occurring in hemodynamics during oxygen respiration under excessive pressure, the authors studied the electrocardiograms, ballistocardiograms, and plethysmograms and determined the pulse wave velocity. Respiration under a pressure of 8-15 mm Hg produced hemodynamic shifts manifested in the increase of the volume of extremities and pulse wave velocity and reduction of systolic complex of the ballisto-cardiogram; however, these changes were insignificant. With a pressure of 20-25 mm Hg, the shifts were pronounced in all the persons tested. With a pressure of 30-40 mm Hg, counter-pressure exerted on the body had a marked effect on normalization of circulation. With respiration under 50-60 mm Hg pressure or more, hemodynamic disturbances could not be completely eliminated, even by counter-pressure on the body.