Acute hemorrhage is a leading cause of death in trauma and women are more susceptible to hypovolemic circulatory stress than men. The mechanisms underlying the susceptibility are not clear however. The aim was to examine the compensatory mechanisms to defend central blood volume during experimental hypovolemia in women and men. Twenty-two women (23.1±0.4 yr) and 16 men (23.2±0.5 yr) were included. Lower body negative pressure (LBNP) of 11-44 mmHg induced experimental hypovolemic circulatory stress. Volumetric technique was used to assess the capacitance response (redistribution of peripheral venous blood to the central circulation) as well as to assess net capillary fluid transfer from tissue to blood in the arm. Plasma Norepinephrine (P-NE) and forearm blood flow were measured before and during hypovolemia and forearm vascular resistance (FVR) calculated. LBNP created comparable hypovolemia in women and men. FVR increased less in women during hypovolemic stress and no association between P-NE and FVR was seen in women (R²=0.01, NS), in contrast to men (R²=0.59, P < 0.05). Women demonstrated a good initial capacitance response, but this was not maintained with time in contrast to men (e.g. decreased with 24±4% (women) vs. 4±5% (men), LBNP 44 mmHg, P < 0.01) and net capillary fluid absorption from tissue to blood was lower in women (0.086±0.007 vs. 0.115±0.011 ml/100ml/min, P < 0.05). In conclusion, women showed impaired vasoconstriction, reduced capacitance response with time and reduced capillary fluid absorption during acute hypovolemic circulatory stress, indicating less efficiency to defend central blood volume than men.