New chlorinated derivatives of mandelamidine and acid addition salts thereof are produced by reacting a mandeliminoalkyl ether of the formula ##EQU1## in which A is alkyl lower alkyl group, preferably C.sub.1 -C.sub.2, and X, Y, Z represent H or Cl, one at least of the X, Y and Z being a chlorine atom, or one of the acid addition salts of the said mandeliminoalkyl ether, preferably the hydrochloride, with an amine of the formula HNR.sub.1 R'.sub.2 in which R.sub.1 is defined as above and R'.sub.2 represents the hydrogen atom, a C.sub.1 -C.sub.5 lower alkyl group, an NH.sub.2 group, an OH group, it being possible for R'.sub.2 to be a (CH.sub.2).sub.n NH.sub.2 group, in which n is an integer having the value 2 or 3 when R.sub.1 = H and, if necessary, the product thus obtained, when R.sub.2 is different from OH, is subjected to an esterification reaction for introducing the group R = acyl. These new derivatives are particularly useful for the treatment of hypertension.

Amidoxime derivatives corresponding to the general formula: ##EQU1## and pharmaceutically acceptable acid addition salts thereof, wherein R.sub.1 and R.sub.2, which are the same or different, represent hydrogen or a straight-chain lower alkyl radical containing from 1 to 3 carbon atoms, n is 0, 1 or 2 and R is selected from the groups consisting of: ##SPC1## Wherein X represents oxygen or sulphur, Y . . . Z represents HC--CH or C=C, R.sub.3 and R.sub.4, which are the same or different, represent hydrogen or a branched- or straight-chain lower alkyl radical containing from 1 to 3 carbon atoms with the provisos that: A. when n is 1, R.sub.1 and R.sub.2 are each hydrogen and R is selected from the groups A, B, C and D. b. when n is 2, R.sub.1 and R.sub.2 area each hydrogen and R is selected from the groups A, B, C and the group D when it represents .beta.-naphthyl. They are effective as antidepressive and antiaggressive agents.