Abstract: The specification describes the total synthesis of L-norleucine-13-motilin ased on the replacement of the L-methionine radical located in the 13-position by an L-norleucine radical. In accordance with the present day development of peptide synthesis the central arginyl-methionyl-bond (amino acids 12 and 13 of motilin) can in practice hardly be synthesised, while on the other hand the norleucine-13-docosapeptide corresponding to motilin can be more readily produced synthetically, and this provides for a comparatively rapid determination of structure and can give important information as regards the biological effect specificity of methionine.