Peripheral postcapillary venous pressure (PCVP) appears to be an indicator of peripheral perfusion (cutaneous blood flow) in the experimental animal. Eighteen male mongrel dogs under balanced anesthesia were subjected to either slow, continuous hemorrhage 0.65 ml/kg/min) or plasma expansion with dextran 40 (0.80 ml/kg/min) over a period of 1 hour. Peripheral PCVP, cental venous pressure arterial pressure, cardiac output (CO), mixed venous oxygen saturation, pulmonary arterial pressure, and pulmonary wedge pressure were monitored on a continuous basis. The only parameter that consistently gave a predictable measure of the degree of induced volume change without requiring pulmonary arterial catheterization was PCVP. PCVP showed a close correlation with CO (r = 0.96).