Summary: The synthesis of CCK-4 (H-Trp-Met-Asp-Phe-NH2) by using enzymes exclusively wasdescribed. As protection group for the amino group we used the Phenylacetyl group (Phac) whichhad been cleaved at the end of the synthesis with Penicillin G Amidase (PGA) without affectingthe peptide bonds. Thus, beginning with Phac-Trp-OH we had successfully synthesized the targetpeptide with following 4 enzymes, α-Chymotrypsin, Papain, Thermolysin and PGA in four reac-tion steps. All reactions were carried out in aqueous buffer in reasonable yields (＞65 %). FAB-MS or FD-MS verified the correct molecular mass of all peptides.