The heptadecapeptide corresponding to the entire amino acid sequence of melaninconcentrating hormone (MCH), isolated from chum salmon pituitaries, was synthesized by successive condensation of four peptide fragments and the N-terminal amino acid, i. e., Boc-(14-17)-OBzl, Boc-(9-13)-OH, Boc-(5-8)-NHNH₂, Boc-(2-4)-NHNH₂ and Boc-Asp (OBzl)-OH, followed by deprotection with 1 M trifluoromethanesulfonic acid-thioanisole in trifluoroacetic acid (TFA) and disulfide formation through the S-sulfonate. When melanin-concentrating activity was measured on a tilapia scale, the minimum effective concentration of the synthetic peptide was equivalent to that of natural salmon MCH (1nM).