The solid phase synthesis of porcine secretin is described. The C‐terminal residue was attached to a polymeric amino support and all the Boc‐amino acids, including Boc‐glutamine, were coupled by a modified carbodiimide method. A preliminary test synthesis showed that the couplings of several amino acids of the N‐terminal section were unsatisfactory. This problem was overcome in the main synthesis by executing all the major reactions twice. Cleavage of the peptide from the resin as well as the removal of all the side chain protecting groups was achieved with liquid HF. The product was purified by ion‐exchange chromatography on SP‐Sephadex to obtain a highly purified heptacosapeptide amide with full biologic