Abstract: The invention is related to new 1,2,3,4,5,6-hexahydro-5-hydroyalkylazepino[4,5-b]-indole derivatives, of formula: ##STR1## in which R.sub.1 denotes a hydrogen atom, an alkyl radical, an alkenyl radical, a benzyl radical, an alkylamino radical of the type ##STR2## where the groups R' are either hydrogen atoms or alkyl radicals or form, together with the nitrogen atom to which they are attached, a heterocyclic nucleus of the morpholinyl, piperidinyl, pyrrolidinyl or piperazinyl type, and m is 2 or 3,R.sub.2 denotes a hydrogen atom or a benzoyl or acyl radical,R.sub.3 denotes a hydrogen atom or an alkyl or benzyl radical,R.sub.4 denotes a hydrogen or halogen atom, an alkyl radical an alkoxy radical or a trifluoromethyl radical, andn is 1 or 2, and the salts of addition to pharmaceutically acceptable acids,and to process for their preparation, to intermediates obtained and to their therapeutical use in treating mental disorders.