1. Urinary kallikrein, sodium, potassium and water excretion, and plasma renin activity were measured before and during the reversal of experimental hypertension produced by unclamping the renal artery in rats.
2. Kallikrein excretion decreased significantly after unclamping, suggesting that it does not play a significant role in the reversal of hypertension.
3. A decrease in plasma renin activity coupled with a slight increase of sodium excretion was observed, indicating that these might participate in the reversal of hypertension.