The syntheses of a series of analogues of the C-tenninal hepta-and octa-peptide of cholecystokinin are described in detail. These peptide and pseudopeptide analogues were obtained by modifying the NIe28-Gly29 region, either by replacing the Gly29 residue by D- Alanine, Sarcosine, or by replacing the peptide bond between Nle28 and Gly29 by a “ketomethylene bond”(COCH2), by a'“carba bond”(CH2CH2) or by a “retro-inverso ...