The binding activity of several galanin fragments and analogs was measured on specific receptors present in rat brain and the rat pancreatic beta cell line Rin m 5F. In both tissues it was observed that: 1) galanin(3-29), galanin(10-29) and [Ile2]-galanin were ineffective for inhibiting [125I] galanin binding and 2) active peptides had the following rank order of potency: galanin(1-29) greater than [Ac-Trp2]-galanin(2-29) greater than galanin(2-29) greater than galanin(1-15) greater than [Phe2]-galanin greater than [Tyr2]-galanin. It was concluded that the N-terminal portion of galanin is very important for interaction with central or peripheral receptors. The aromatic amino acid in position 2 (Trp in native galanin) plays a crucial role.