Herbicidal new substituted imidazolinylpyrimidines of the general formula (I) ##STR1## in which R.sup.1 represents hydrogen, halogen, cyano, nitro or thiocyanato, or represents a hydroxyl, mercapto, amino, carbonyl, sulphinyl, sulphonyl, alkyl, alkenyl, alkinyl, cycloalkyl, cycloalkenyl, aryl or heterocyclyl radical, each of which is optionally substituted,R.sup.2 represents hydrogen, hydroxyl, halogen, alkyl or halogenoalkyl,R.sup.3 represents hydrogen, or represents alkyl, alkenyl, alkinyl, cycloalkyl, cycloalkenyl, aryl or heterocyclyl, each of which is optionally substituted, or represents an equivalent of an inorganic or organic cation,R.sup.4 and R.sup.5 independently of each other in each case represent hydrogen, alkyl, halogenoalkyl or cycloalkyl andX represents oxygen or sulphur.