Adrenomedullin is a 52-amino acid peptide that was first isolated from human pheochromocytoma. Subsequently, it was found to be distributed widely in the body, including throughout the cardiovascular system. It belongs to a family of peptides that include calcitonin gene-related peptide and amylin. Adrenomedullin causes vasorelaxation and influences vascular proliferation and interacts closely with nitric oxide, and it may have a role in the pathophysiology of hypertension, ischemic heart disease, and cardiac and renal failure. Nonpeptide agonists or antagonists of adrenomedullin may have potential therapeutic application. The role of adrenomedullin in septicemic shock also merits further investigation.