Syntheses of analogues of the C-terminal heptapeptide of cholecystokinin are described. These analogues were obtained by replacing glycine 29 by a beta-alanine. The C-terminal phenylalanine amide was in some cases substituted by 2-phenylethyl alcohol and/or residues of the C-terminal tetrapeptide by their D-enantiomers. These compounds were tested for their action on stimulation of amylase release from rat pancreatic acini and for their ability to inhibit binding of labeled CCK to rat pancreatic acini and guinea pig brain membranes. Some of these derivatives behaved as CCK receptor antagonists.