Abstract: The invention relates to the preparation of biologically active polypeptides containing the aspartyl group, particularly an aspartyl-glycine moiety, using the active-ester technique.According to the method of the invention, human adrenocorticotropic hormone and its fragments characteristic to the individual species, as well as the blocked derivatives of such compounds are prepared by the pentafluorophenol method, i.e., the carboxy group of the acylating component is activated by converting it into pentafluorophenyl ester in the coupling reaction carried out with blocked peptides containing the aspartyl group or an aspartylglycine moiety. The acylation is carried out preferably using equimolar quantities of the respective reactants. The free peptides obtained after removing the blocking groups can be converted into their acid addition salts or pharmaceutically acceptable complexes or condensates.Human adrenocorticotropic hormone and its derivatives are valuable substances of therapeutical activity.