Novel triarylphosphinimide derivatives having the formula ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 are each at the ortho or meta position, represent mono- or disubstituents and are selected from the group consisting of hydrogen, alkyl(C.sub.1 -C.sub.3), alkoxy(C.sub.1 -C.sub.3), trifluoromethyl and halogen; and R.sub.4 is selected from the group consisting of alkyl(C.sub.1 -C.sub.3), alkenyl(C.sub.2 -C.sub.3), alkynyl(C.sub.2 -C.sub.4), cycloalkyl(C.sub.3 -C.sub.5), cycloalkyl(C.sub.3 -C.sub.6)methyl, 4-oxopentyl, 3-tetrahydrofuranyl, 2,3-dihydro-1H-inden-1-yl, 1-alkyl(C.sub.1 -C.sub.3)cyclopentyl, trans-2-alkyl(C.sub.1 -C.sub.3)cyclopentyl, trans-2-alkoxy(C.sub.1 -C.sub.3)cyclopentyl, 1-cyclopropylethyl, 2-methylcyclopropylmethyl, dicyclopropylmethyl, 2-, 3- or 4-pyridinylmethyl, 2-cyclopenten-1-yl, tetrahydro-2H-pyran-4-yl and cis and trans-2-methoxycyclohexyl; with the proviso that when R.sub.4 is alkyl(C.sub.1 -C.sub.3), R.sub.1, R.sub.2 and R.sub.3 may not each be hydrogen ##STR2## wherein R.sub.1, R.sub.2 and R.sub.3 are each at the ortho or meta position and are selected from hydrogen and alkyl(C.sub.1 -C.sub.3), and X is an acid addition salt; processes for producing them, compositions containing them, and methods for using them in mammals to effect diuresis; to lower plasma renin levels and to increase cardiac contractility.