Schizophrenic patients have been subjected to severe anoxia over a period of several mins. either up to the point of unconsciousness or in some cases extending into unconsciousness. The following conclusions are drawn: Anoxia of severe degree produces no beneficial effects on the mental condition of this class of psychotic patients. Anoxia severe enough to produce brief periods of unconsciousness has no lasting harmful effects on the C. N. S. Respiratory stimulation by anoxia is strong and sustained even during unconsciousness. In-ferentially, circulatory function is also well sustained. There is a remarkably rapid return to normal when either air or 14% oxygen is supplied. A mixture of 4.2% oxygen with nitrogen is equivalent physiologically to an altitude of about 31,000 feet. It should be possible to descend with an opened parachute from 31,000 feet altitude without oxygen equipment with no ill effects from anoxia.