Abstract: The invention relates to novel .beta.-carboline-derived compounds which are benzodiazepine-receptor ligands having an inverse agonist and antagonist effect on benzodiazepines. These compounds are of the formulae: ##STR1## in which: X is O, S, ##STR2## or alternatively, ##STR3## represents the radical --N(R.sub.6)--C(=O)--CH.sub.2 --X, R.sub.1 is a hydroxyl, alkoxy or alkyl radical substituted by a hydroxyl or alkoxy radical,R.sub.2 is a hydrogen atom or an alkyl, hydroxyl, alkoxy, acyloxy or benzyloxy radical, it being possible for said radicals to be optionally substituted,R.sub.3, R.sub.4, R.sub.5 and R.sub.6 are chosen from a hydrogen atom or an alkyl radical optionally substituted by a hydroxyl, alkoxy or alkoxycarbonylmethyl radical,as well as the corresponding tetrahydro derivatives of .beta.-carboline and the quaternary ammonium salts or derivatives of these pharmaceutically acceptable compounds.