Summary The effect of epinephrine injected into the renal artery has been studied as a model for the assessment by angiography and xenon washout of the control and relative responsiveness of the renal cortical vasculature to such stimuli in man and to ascertain whether a quantitatively significant shunt mechanism can be demonstrated in the human kidney. The findings suggested a dominant sensitivity of the cortical vasculature and rule out the presence of a quantitatively significant shunt mechanism in this setting. The pattern of recovery from the effects of epinephrine suggests that patchy areas in the cortex recover a normal rate of perfusion while other areas remain extremely vasoconstricted. This pattern of perfusion appears to be characteristic of the kidney in a large number of clinical situations.