The purpose of the present experiment was to determine the functional subclassification of renal adenosine receptor fer the hemdynamic, excretory and secretory functions in unanesthetized rabbits. Adenosine antagonist, 8-phenyltheophylline (8-PT) or theophylline, was infused into the left renal artery followed by an infusion of adenosine agonist, cyclohexyladenosine (CHA) or 5 -N-ethylcarboxamidoadenosine (NECA). Intrarenal arterial infusion of CHA or NECA caused decreases in urine volume, glomerular filtration rate, renal plasma flow and excreted amount of electrolytes and renin release in a dose-dependent manner. Dose-response curves in renal function by CHA or NECA was similar and shifted to the right with pretreatment of 8-PT or theophylline. No significant differences in renal response to CHA and NECA in antagonist-treated rabbits were observed. However, the decrease in renin secretion rate was not affected by the adminstration of adenosine antagonists. These results suggest that the renal effect of adenosine receptor agonists appears by way of specific adenosine receptor, but which is not functionally subclassified in the rabbit.