A linear peptide which is an analog of naturally occurring, biologically active substance P having an active site and a binding site responsible for the binding of said peptide to a receptor on a target cell. The analog has a non-peptide bond instead of a peptide bond between an amino acid residue of said active site and an adjacent amino acid residue, or a synthetic, a β-amino acid, or a η-amino acid residue replacing two amino acid residues of the active site.