Abstract: Bivalent agonists having affinity for one or more G-protein coupled receptors, comprising two agonist or two antagonist ligand domains, wherein the distance between the ligand domains can range from about 40 to about 250 Å, and further comprising a backbone, wherein the backbone is covalently bonded to the two ligand domains, are provided. Additionally, bivalent agonists are provided that comprise one agonist and one antagonist ligand domain. In a specific embodiment, the bivalent agonists are peptide dimers, wherein the backbone comprises two spacer regions, two polylysine regions, and a disulfide bond region, such that the order in which the ligand domains, spacer regions, polylysine regions and disulfide bond region are covalently bonded together is: (ligand domain)-(spacer region)-(polylysine region)-(disulfide bond region)-(polylysine region)-(spacer region)-(ligand domain). Such peptide dimers are prepared from oxidative dimerization of their corresponding monomers.