1. The effect of angiotensin II-amide upon the intrarenal distribution of perfusate was studied in the isolated rat kidney.
2. Low concentrations of angiotensin, 4·86 pmol/l (0·005 μg/l), reduced the flow rate through the papilla but did not alter total flow.
3. Higher concentrations of angiotensin, 0·486 nmol/l (0·5 μg/l), reduced total renal flow but did not decrease papillary perfusion.
4. In these experiments the perfusion pressure was maintained constant, indicating that the changes in flow were due to a direct effect of angiotensin upon the renal vasculature.