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It is well documented that exposure to a hypoxic environment affects visual and auditory perception and attenuates cognitive function in humans. Since the perception of thermal stimuli is indispensable for appropriate behavioral protection against cold in both low and high altitudes, the present study examined if and how hypoxia affects the perception of cold stimuli in humans. The perception of thermal stimuli depends on the unimpeded activity of temperature receptors. The perception of cold was determined on the plantar surface of the first two toes during exposure to normobaric hypoxia. The perception of cold was tested twice, once under hypocapnic, and once during normocapnic conditions. The study was composed of two separate trials. In both trials, the subjects (N = 13) inhaled a hypoxic mixture equivalent to 5,500m (PIO2 = 0.10 atm). In one trial (normocapnia), CO2 was added to the inhaled gas mixture in order to maintain the normal, normocapnic value of CO2 in the exhaled air. In the second trial (hypocapnia), CO2 was not added to the breathing mixture. In both trials, the cutaneous threshold for cold sensation was determined prior to and during exposure to hypoxia. The statistical analysis was performed with one-way analysis of variance for correlated samples. The threshold for cold sensation increased significantly during hypoxia, under both hypocapnic and normocapnic conditions. The cold sensation threshold increased from 4.7 (3.2) °C to 6.3 (3.5) °C during hypocapnia, and from 4.7 (3.2) °C to 6.2 (3.2) °C during normocapnic conditions. Sensitivity to cold thus decreased during hypoxia, as the perception of cold stimuli was attenuated. It is concluded that hypoxia attenuates the perception of cold, which may in turn lead to greater susceptibility to hypothermia and cold injury at high altitudes.