Herbicidally active novel substituted 1-benzylsulphonyl-3-heteroaryl(thio)-ureas of the formula ##STR1## in which Q represents oxygen or sulphur,R.sup.1 represents hydrogen, or represents optionally substituted radicals from the series comprising alkyl, alkenyl, alkynyl and aralkyl,R.sup.2 represents hydrogen, halogen, hydroxyl, alkyl, halogenoalkyl, alkoxy, halogenoalkoxy, alkylthio, halogenoalkylthio, amino, alkylamino or dialkylamino,R.sup.3 represents hydrogen or alkyl,R.sup.4 represents halogenoalkyl,X represents nitrogen or a --CH grouping,Y represents nitrogen or a --CR.sup.5 grouping,R.sup.5 represents hydrogen, halogen, cyano, alkyl, formyl, alkyl-carbonyl or alkoxy-carbonyl,Z represents nitrogen or a --CR.sup.6 grouping, andR.sup.6 represents hydrogen, halogen, hydroxyl, alkyl, halogenoalkyl, alkoxy, halogenoalkoxy, alkylthio, alkylamino or dialkylamino,and salts thereof with metals and basic organic nitrogen compounds. The benzylsulphonyl moieties are also new.