Herbicidal aminoguanidinoazines of the formula ##STR1## in which R.sup.1 stands for an optionally substituted radical from the series comprising alkyl, aralkyl, aryl and hetaryl,R.sup.2 stands for hydrogen, halogen, hydroxyl, alkyl, halogenoalkyl, alkoxyalkyl, alkoxy, halogenoalkoxy, alkylthio, halogenoalkylthio, amino, alkylamino or dialkylamino,X stands for nitrogen or a --CH group,Y stands for nitrogen or a --CR.sup.3 group whereR.sup.3 stands for hydrogen, halogen, cyano, alkyl, formyl, alkyl-carbonyl or alkoxy-carbonyl, andZ stands for nitrogen or a --CR.sup.4 group whereR.sup.4 stands for hydrogen, halogen, hydroxyl, alkyl, halogenoalkyl, alkoxy, halogenoalkoxy, alkylthio, alkylamino or dialkylaminoand their salts,with the exception of the compounds N'-(4,6-dimethyl-pyrimidin-2-yl)-N"-amino-N'"-(2-diethylaminosulphonyl-phenylsulphonyl)-guanidine, N'-(4,6-dimethyl-pyrimidin-2-yl)-N"-amino-N'"-(2-methoxycarbonyl-phenylsulphonyl)-guanidine and N'-(4,6-dimethyl-pyrimidin-2-yl)-N"-amino-N'"-(2-methoxycarbonyl-thiophen-3-yl-sulphonyl)-guanidine and their salts.