Supportlessness arising as a result of 7 hrs dry immersion is accompanied by decreased transverse stiffness and increased calf venous compliance, as well as impaired orthostatic tolerance. Stimulation of support zones of foot is associated with smoothening of these effects. The latter may be considered as an indirect evidence in favor of the concept of support deafferentation triggering role in development of enumerated unfavorable effects of simulated microgravity.