Abstract: Ethylamine derivatives of the formula (I): (wherein R1 is hydrogen, hydroxyl, lower alkoxy or halogen; R2 is alkyl having 2 to 5 carbon atoms; R3 is hydrogen, alkyl having 2 to 5 carbon atoms, alkylcarbonyl having 2 to 5 carbon atoms, aryl having 6 to 10 carbon atoms or arylalkyl having 7 to 11 carbon atoms; the ring is a bicyclic compound which consists of at least one benzene ring and may comprise a saturated or unsaturated five- or six-membered ring which may or may not have heteroatoms, providing that when the ring is indole or 1,3-benzodioxole, R2 and R3 do not constitute, at the same time, two carbon atoms members, and when R3 is hydrogen, the ring is a bicyclic compound which is not indole, benzothiophene or benzodioxole and R2 is alkyl having 3 to 5 carbon atoms and pharmaceutically acceptable acid addition salts thereof. These compounds are promising as psychotropic drugs, antidepressants, drugs for Parkinson's disease and/or drugs for Alzeimer's disease.