Cationic azo dyestuffs of the general formula ##STR1## wherein X.sup.(+) denotes an ammonium group,m denotes 0 or 1,R.sub.1 denotes hydrogen, C.sub.1 - to C.sub.4 -alkyl, C.sub.1 - to C.sub.4 -alkoxy or halogen,R.sub.2 and R.sub.3 independently of one another denote hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 - to C.sub.4 -alkoxy or acylamino,Z denotes halogen or a radical of the formula ##STR2## R.sub.4 and R.sub.5 independently of one another denote hydrogen, or C.sub.1 - to C.sub.4 -alkyl, cyclohexyl, phenyl, benzyl or phenylethyl, it being possible for these radicals to be substituted by hydroxyl, C.sub.1 - to C.sub.4 -alkoxy, chlorine or cyano and for the cyclohexyl, phenyl, benzyl and phenylethyl radical additionally to be substituted by C.sub.1 - to C.sub.4 -alkyl, orR.sub.4 and R.sub.5, together with the nitrogen atom to which they are bonded, denote a 5- or 6-membered ring,A denotes an aryl radical andAn.sup.(-) denotes an anion,are suitable for dyeing synthetic and natural materials.