1. Human renal renin has been purified 200 000-fold from cadaver kidney cortex by a method which employs affinity chromatography on aminohexyl pepstatin.
2. The product of this purification has a specific activity of 400 Goldblatt units/mg when compared with Haas human renin standard.
3. This product appears as a single band on sodium dodecyl sulphate gel and polyacrylamide-disc gel electrophoresis. Renin enzymatic activity was recovered after elution from a polyacrylamide-disc gel run at pH 7·8.
4. Yield with this method was 1%.