Selective infusion of the epinephrine into the renal artery has been used in the field fo the diagnostic andthe therapeutic radiology for correct diagnosis and effective treatment, respectively. However, administration ofoverdose of epinephrine may cause serious complication, renal infarction. The study was undertaken to evaluate thesequential change of renal arterial constrictive effect of selective infusion of epinephrine into renal artery andto determine the critical doses of epinephrine producing irreversible renal infarct. A total of 25 rabbits areused, which are devided into 5 groups. Under the general anesthesia is made the selective infusion of variousdoses of epinephrine into the right renal arter of the rabbits. At the various time interval during and after theepinephrine infusion, renal angiography was doen, and 24 hrs. later, gross and microscopic findings of the kidneywere observed. The results are as follows; 1. Vasoconstriction of renal artery occurred within 2 mins. infusion,and maximum effect within 5 mins. 2. It seems that there is correlation between the amount of infused epinephrineand the time taken to recover from constiction of renal artery. 3. When epinephrine is infused into the renalartery in the rate of 1ug/min., renal infarct is not noticed below the level of 10 mins., but correlation betweenthe amount of infused epinephrine and the frequency of renal infarct occures above 20 mins. infusion.