Angiotensin II, adminstered (infused or injected) intravenously, elicited the antidiuretic action with the decreased parameters of renal function at a small dose ($0.01;{mu}g/kg/min$), whereas, at a large dose (0.03, $0.1;{mu}g/kg/min$ and $5.0;{mu}g/kg$), it produced the diuretic action accompanied the increased amounts of sodium and potassium excreted in urine ($E_{Na};and;R_K$). At this time, glomerular filtration rates (GFR) were weakened slightly and renal plasma flows (RPF) were reduced markedly, and then filtration fractions (FF) were increased. Angiotensin II, infused into a renal artery, exhibited antidiuretic action at a small dose ($0.003;{mu}g/kg/min$), and diuretic action at a large dose ($0.01;{mu}g/kg/min$), only in infused (experimental) kidney. The mechanism of the action was similar to the cases of the intravenous angiotensin II. The above results suggest that angiotensin II of a large dose produced diuretic action due to mechanism inhibiting reabsorption of electrolytes in renal tubules, mainly in proximal tubule in dog.