Herbicidally active 2,4-diamino-6-haloalkylpyrimidines of the formula ##STR1## in which R.sup.1 and R.sup.3, independently of one another, represent hydrogen or alkyl,R.sup.2 and R.sup.4, independently of one another, represent hydrogen, alkyl which is optionally substituted by halogen, cyano, alkoxy, alkylthio or by cyclopropyl, represent cycloalkyl, alkenyl which is optionally substituted by halogen, or alkinyl, andR.sup.5 represents alkyl which is substituted by halogen, with the proviso that R.sup.1, R.sup.2, R.sup.3 andR.sup.4 do not simultaneously represent hydrogen whenR.sup.5 represents trichloromethyl, and with the provisio that R.sup.1 and R.sup.2 do not simultaneously represent hydrogen when R.sup.4 represents alkyl which is substituted by alkoxy or alkylthio.