Although total body cooling has now been under scientific study for about a century and has been of particular neurological interest during the last decade, it has not yet met with universal neurosurgical acceptance. We do not have precise indications for its present clinical use, nor do we have a clear idea of its future. Many significant facts, however, have been established. Hamsters have been frozen until ice crystals have formed in their tissues; mice, monkeys and dogs have been reduced to nearly O C, until all detectable heart and respiratory action have ceased, yet all these animals have survived.1Man has been shown to withstand temperatures between 29.4 and 32.2 C for as long as 10 days and temperatures above 25 for a shorter period, but the safe lower limits of human hypothermia have not yet been established.3 During this total body cooling, oxygen consumption of the