(NASA CR-329, 406pp, soft cover, stapled) As part of its experiments in preparation for manned flight, eight chimpanzees were decompressed in nine separate tests from 179mm Hg (100 per cent oxygen) to less than 2mm Hg in 0.8 seconds and remained at this pressure from 5 to 150 seconds. After recompression to 179 mm Hg (again breathing 100 per cent oxygen), the subjects were kept at this altitude for 24 hours." This NASA report presents the nature and outcome of these experiments as measured by behavior and the implications from the lessons learned for human spaceflight. Very good condition with modest toning on the green cover. Rare.