A series of dipeptide analogues of angiotensinogen have been prepared and evaluated for their ability to inhibit the aspartic proteinase renin. The compounds were derived from the renin substrate by replacing the scissile amide bond with a transition-state mimic and by incorporating bioisosteric replacements for the Val-10 amide bond. Analogue 21a exhibited an IC50 of 7.6 nM against purified human renin, showed high specificity for this enzyme, and produced a hypotensive response in anesthetized, salt-depleted cynomolgus monkeys.