The actions of Atractylodes rhizoma alba on renal function of dog were investigated with water and methanol extract of it, utilizing clearance technique. Water extract elicited diuresis while methanol extract induced antidiuresis in the dog when they were given intravenously. The diuresis induced by the intravenous water extract seemed to be closely related to the decrement of reabsorption of electrolytes in renal tubules. On the contrary, the antidiuresis by intravenous methanol extract appeared to be related to the increment of renal reabsorption of sodium. Water and methanol extract, when infused into a renal artery, exhibited identical resposes to the intravenous actions confined only to the infused kidney, inferring that renal actions of water and methanol extract are not mediated by any endognous humoral extract are not mediated by any endogenous humoral agents. From these observations it is concluded that diuretic action of water extract and antidiuretic action of methanol extract were brought about by direct action in the renal tubules.