This report presents the results of physiological testing of some anti-exposure suits, either currently in the Air Force inventory or being considered for the inventory, as part of a "Life Saving System." The tests were carried out both in an Alaskan river with water temperatures of 0°, 2°, 7° and 12° C and air temperatures of -18°, 1°, 12° and 15° C, and in a temperature-controlled box at an air temperature of -30° C with a water temperature of 0° C. The suits tested were the RI-A, the CWU-3/P and the CWU-12/P. After being instrumented so as to obtain skin and rectal temperatures, between six and eight subjects wore each of the clothing assemblies under simulated water survival conditions. The subjects jumped into cold water, then boarded and remained in an MB-4 one-man life raft for 2 hours or until rectal temperature fell to 35° C. The nearly linear falls of rectal temperature with time were extrapolated to 31° C, a reasonable cut-off temperature, and this time was termed "estimated survival time." By this method it was determined that the rectal temperatures of subjects dressed in the CWU-12/P in 12° C water and 15° C air would reach 31° C in 15 hours. The severely hypothermic subject would then be revivable in a tank of warm water at 41° to 42° C. On the basis of these experiments, it is recommended that the Air Force substitute an insulated raft for the MB-4's currently in the inventory. Insulation in the floor and canopy of the raft will markedly increase survival time. The results of the testing program in the cold box at -30° C showed that vapor-impermeable anti-exposure suits are unsuitable for cold land survival. The suits must be removed and a down-filled arctic survival garment donned under these conditions.