Cerebral, hepatic, renal cortical, and medullary tissue blood flows of the dog during hemorrhagic shock were measured continuously using the thermoelectrical method. The effects of blood replacement, adrenergic α-stimulator and -blockade and hydrocortisone on the tissue blood flows were studied.After hemorrhage, cerebral blood flow was well maintained while renal cortical blood flow was poorly maintained. Following retransfusion, the blood flow returned rapidly to the brain and slowly to the renal cortex. Norepinephrine, phentolamine, and hydrocortisone were not effective in maintaining the organ blood flows in shock. However, when norepinephrine was given systemically and phentolamine administered to the renal artery simultaneously during shock, both cerebral and renal flows were well maintained. After the blood replacement and administration of α-blockade or hydrocortisone, all the measured blood flows returned to normal levels.