Respiratory sensation was studied in seven European lowlanders during a Himalayan expedition at over 6000 m. At rest, the ability to detect added inspiratory resistive loads can be used to create a sensitivity index P(A) taking response bias (B) into account based on Sensory Decision Theory. The data indicate that respiratory sensitivity may be involved in successful adaptation to hypoxia. Respiratory sensitivity improved during the first stages of exposure to altitude and returned to baseline after 17- and 27-day stays under chronic hypoxic conditions. The improvement in respiratory sensation could be a primary signal in the physiological and psychological adaptation to high altitude and change in sensation may reflect the degree of altitude adaptation.