An N-acylamino acid derivative of the formula: ##STR1## wherein each of R.sup.1, R.sup.2, R.sup.4 and R.sup.6 is hydrogen lower alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl or a monocyclic or bicyclic heterocyclic group containing from to 4 hetero atoms; each of R.sup.3 and R.sup.5 is hydrogen or lower alkyl; A is --CH(OH)--(CH.sub.2).sub.q R.sup.7 wherein R.sup.7 is hydrogen, lower alkyl, cycloalkyl, cyloalkylalkyl, aryl, aralkyl, a monocyclic or bicyclic heterocyclic group containing from to 4 hereto atoms or --E--R.sup.10 wherein E is --S(O).sub.i -- wherein i is 0, 1 or 2, oxygen, --NR.sup.11 -- wherein R.sup.11 is hydrogen, lower alkyl, cycloalkyl, cycloalkylalkyl, aryl or aralkyl, or ##STR2## wherein each of R.sup.12 and R.sup.13 is hydrogen, lower alkyl cycloalkyl, cycloalkylalkyl, aryl or aralkyl, and R.sup.10 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 R.sup.10 is hydrogen, i is 0, and a is an integer of from 0 to 5; or --CH.sub.2 --CHR.sup.8 --CO--R.sup.9 wherein R.sup.8 is hydrogen, lower alkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl or a monocyclic or bicyclic heterocyclic group containing from 1 to 4 hetero atoms, and R.sup.9 is hydroxyl, --OX wherein X is alkyl, aryl, lower alkoxycarbonyloxyalkyl or 1-phthalidyl, or --N(Y.sup.1) (Y.sup.2) wherein each of Y.sup.1 and Y.sup.2 is hydrogen, lower alkyl, aryl, aralkyl or cycloalkyl, or Y and.sup.1 and Y.sup.2 form together with the adjacent nitrogen atom a 5- or 6-membered heterocyclic group which may contain a further hereto atom; m is 0, 1 or 2; and n is an integer of from 1 to 5, provided that when R.sup.1 is hydrogen, m is 0; or a salt thereof, which is useful as hypotensive drugs.