Abstract: Peptides of formula: ##STR1## in which X=H or a radical which protects the amine gorup, R=H or SO.sub.3 H, A an D are:either different, and one of them donotes a radical ##STR2## and the other a radical ##STR3## m and n being between 1 and 5, and A and D form a ring by amidation of their side chains,or identical or different and denote: ##STR4## with p=1 or 2, and A and D form a ring by oxidative bridging between the sulfphur atoms; B and E=Met, NLe, Leu, Ser, Thr, allo-Thr, or Cys or Hcy, in which the OH or SH groups are free or protected;F=valency bond or Phe, Tyr(OCH.sub.3) or Cha;Q=H or alkyl (1 to 6 C), phenyl or phenylalkyl, these radicals being unsubstituted or substituted with fluorine atoms, and the amino acids are D, L or DL; are useful, in particular, as enuropsychotropic drugs.