C-type Natriuretic Peptide (CNP), is the third member of the natriuretic peptides family, already composed of ANP and BNP. It was called C-type NP to maintain the alphabetical nomenclature of natriuretic peptides. It is the most conserved NP among species. It is derived from a 126 amino acid preprohormone. CNP exists as two mature forms, one found in tissues, the other in plasma and cerebrospinal fluid. It is present in high concentration of the vascular tree, especially the endothelium, central nervous tissues, and renal tubular cells. It is a powerful vasorelaxant and inhibitor of smooth muscle cell proliferation, and it may play a role in coagulation and fibrinogenesis by modulating endothelial cells.