The heptadecapeptide amide, [graphic omitted]lu-Gly-Pro-Trp-Val-Glu-Glu-Glu-Glu-Ala-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH₂(I), has been synthesised and shown to be identical with natural ovine-bovine gastrin I. Partial nitrosation of tryptophyl residues was detected during earlier attempts to synthesise (I) by routes involving azide couplings.