A 4,5-dichloro-imidazole derivative of the formula ##STR1## in which X represents trifluoromethyl, cyano or a ##STR2## or ##STR3## in which R.sup.1 represents a saturated or unsaturated aliphatic radical, which can be carrying one or more substituents selected from halogen, alkoxy with 1 to 6 carbon atoms and alkylmercapto with 1 to 6 carbon atoms,R.sup.2 represents hydrogen, alkyl with 1 to 8 carbon atoms, alkenyl with up to 8 carbon atoms or the formyl group,R.sup.3 represents hydrogen, alkyl with 1 to 8 carbon atoms or alkenyl or alkynyl each with up to 8 carbon atoms, it being possible for each of these alkyl, alkenyl and alkynyl radicals to carry one or more substituents selected from alkoxy with 1 to 4 carbon atoms, alkylmercapto with 1 to 4 carbon atoms, phenyl (which may optionally carry one or more substituents selected from halogen, alkyl with 1 to 4 carbon atoms, trifluoromethyl and alkoxy with 1 to 4 carbon atoms), furyl or thienyl, or represents cycloalkyl with 5 to 7 carbon atoms in the ring which is optionally substituted by alkyl with 1 to 6 carbon atoms, or represents phenyl which may optionally carry one or more substituents selected from halogen, alkyl with 1 to 4 carbon atoms, alkoxy with 1 to 4 carbon atoms, alkylmercapto with 1 to 4 carbon atoms and trifluoromethyl, orR.sup.2 and R.sup.3 conjointly with the adjoining nitrogen atom form an optionally substituted 5-membered to 7-membered heterocyclic ring in which 1 to 3 ring members may be selected from oxygen, sulphur and nitrogen, andR represents alkyl with 1 to 12 carbon atoms or alkenyl or alkynyl each with up to 12 carbon atoms, it being possible for each of these alkyl, alkenyl and alkynyl radicals to carry one or more substituents selected from halogen, alkoxy with 1 to 6 carbon atoms, alkylmercapto with 1 to 6 carbon atoms, cycloalkyl with 5 to 7 carbon atoms in the ring and phenyl (which itself optionally carries one or more substituents selected from alkyl with 1 to 6 carbon atoms, alkoxy with 1 to 6 carbon atoms, halogen and trifluoromethyl), or represents cycloalkyl with 5 to 7 carbon atoms in the ring or represents a phenyl radical which is at least disubstituted; and the use of such novel 4,5-dichloro-imidazole derivatives as plant protection agents especially as a herbicide, plant growth regulant, insecticide or acaricide.