The present experiment was designed to investigate renal function in conscious rabbits. Pentobarbital caused some reduction of urinary volume and hemohynamics, but the changes were not significant. UnaV, UkV, UclV were not changed by pentobarbital in dose of 3.0~9.0mg/kg i.v.. Urinary flow snd UclV were not changed by pentothal sodium, 5.0mg/kg i.v., but the UnaV and UclV increased from 30.61 to 66.19 uEq/min, from 28.29 to 62.91 uEq/min respectively, after pentothal sodium. There was no change in urinary potassium secretion after pentothal sodium. Left renal arterial infusion of pentothal sodium caused small changes in GFR, and clear increments of UnaV and UclV localized in that kidney in the urethane anesthetized rabbit. Natriuretic and chloruretic effect of pentothal sodium were not seen in mannitol diuresis. These data suggest that 1) the effects of pentobarbital and pentothal may not be the sam in conscious rabbit renal function, 2) natriuretic and chloruetic effect by pentothal may be caused by direct inhibition of sodium reabsorption in the distal nephron in the rabbit.