Abstract: The L-proline derivatives of the invention correspond to the Formula I: ##STR1## in which R.sub.1 corresponds to the Formula II: ##STR2## in which R is a carbonyl group, an acyl group --Y--CO-- or an oxy-acyl group --O--Y--CO--, Y being an alkyl or an alkenyl chain, Z being one or more hydrogen atoms, or one or more substituents chosen from among halogen atoms, CF.sub.3, alkyl or alkoxy groups and an alkylenedioxy group in the case of two neighbouring substituents,R.sub.2 is --NH.sub.2, --OH, or a derivative of these groups,A.sub.1 and A.sub.2 are amino acid residues andB.sub.1 and B.sub.2 represents a hydrogen atom or a methyl group, and the pharmacologically acceptable salts of these derivatives.These derivatives are useful particularly as the active principles of medicines possessing, in particular, a nootropic action.