An N-acylamino acid derivative of the formula:
wherein each of R¹, R², R⁴ and R⁶ is hydrogen, lower alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl or a monocyclic or bicyclic heterocyclic group containing from 1 to 4 hetero atoms; each of R³ and R⁵ is hydrogen or lower alkyl; A is -CH(OH)-(CH₂) q R⁷ wherein R⁷ is hydrogen, lower alkyl, cycloalkyl, cyloalkylalkyl, aryl, aralkyl, a monocyclic or bicyclic heterocyclic group containing from 1 to 4 hetero atoms or -E-R¹⁰ wherein E is -S(O) i - wherein i is 0, 1 or 2, oxygen, -NR¹¹- wherein R¹¹ is hydrogen, lower alkyl, cycloalkyl, cycloalkylalkyl, aryl or aralkyl, or
wherein each of R¹² and R¹³ is hydrogen, lower alkyl, cycloalkyl, cycloalkylalkyl, aryl or aralkyl, and R¹⁰ is hydrogen, lower alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl or a monocyclic or bicyclic heterocyclic group containing from 1 to 4 hetero atoms provided that when R¹⁰ is hydrogen, i is 0, and q is an integer of from 0 to 5; or -CH₂-CHR⁸-CO-R⁹ wherein R⁸ is hydrogen, lower alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl or a monocyclic or bicyclic heterocyclic group containig from 1 to 4 hetero atoms, and R⁹ is hydroxyl, -OX wherein X is alkyl, aryl, lower alkoxycarbonyloxyalkyl or 1-phthalidyl, or -N(Y¹)(Y²) wherein each of Y¹ and Y² is hydrogen, lower alkyl, aryl, aralkyl or cycloalkyl, or Y¹ and Y² form together with the adjacent nitrogen atom a 5- or 6-membered heterocyclic group which may contain a further hetero atom; m is 0, 1 or 2; and n is an integer of from 1 to 5, provided that when R¹ is hydrogen, m is 0; or a salt thereof, which is useful as hypotensive drugs.