Abstract: There are provided peptides of the formulaX-Val-Pro-Leu-Gly-Trp-A-Ywherein X represents a hydrogen atom or a terminal nitrogen protecting group, A represents a neutral L-.alpha.-amino acid residue and Y represents OH, NH.sub.2 or a group of the formula OR, NHR, NR.sub.2 or NHNHR' wherein R represents a C.sub.1 -C.sub.11 alkyl group optionally substituted, a C.sub.7 -C.sub.14 aralkyl or a phenyl group and R' represents H, any of the groups which R may represent or a protecting group. Pharmaceutically or veterinarily acceptable salt of these peptides are also provided, as are pharmaceutical or veterinary compositions containing peptides or their salts. The peptides which can be prepared by classical solution synthesis, display useful activity on the central nervous system and are active as growth promotors.