The enzymatic hydrolysis of angiotensin I and II is reviewed briefly with emphasis on two enzymes, the angiotensin I converting enzyme and neutral endopeptidase 24.11. Angiotensin I is converted to angiotensin II by converting enzyme present in many tissues and highly concentrated in the human kidney and in kidney of some laboratory animals. In addition, there is mounting evidence, collected mostly in experiments in vitro, that other enzymes may be able to activate angiotensin I, for example by the stepwise release of the C-terminal His and Leu residues. Angiotensin I, instead of being activated, could be inactivated by the cleavage of its C-terminal tripeptide either by neutral endopeptidase 24.11 or by prolyl endopeptidase. Angiotensin II is cleaved by several peptidases widely distributed in the kidney. One of the products, des-Phe8-angiotensin II, is not entirely inactive as it has an effect in the CNS.