Resin peptides useful in preparing peptides having biological activity, and particularly such resin peptides containing ALA-GLU-CH.sub.2 - R at one end of an amino acid chain, R being the resin and ALA and GLU being the residues of the amino acids alanine and glutamic acid; and processes for the preparation of such resin peptides. Resin peptides including ACTH.sup.1-28 are disclosed which have adrenocorticotropic activity along with processes for their preparation.