Benzimidazole derivatives corresponding to the formula (I) ##STR1## in which X is CH or N,R.sub.1 is either a hydrogen atom, or a benzyl radical which can bear 1 to 3 substituents chosen from halogen atoms and trifluoromethyl, (C.sub.1-4)alkyl, (C.sub.1-4)alkoxy, cyano, methylthio, methylsulphinyl and methylsulphonyl radicals, or a methyl radical bearing a heterocyclic substituent in which the heterocyclic system can be a pyridyl, thienyl or furyl radical and can bear one or more substituents,R.sub.2 is a hydrogen atom or a (C.sub.1-4)alkyl radical,R.sub.3 is a hydrogen atom or a hydroxy radical, andR.sub.4 is a hydrogen atom or a (C.sub.1-4)alkyl radical, where appropriate, in tautomeric form when R.sub.3 is OH.The compounds may be used in treating allergy and histamine-induced inflammation.