Arginine Vasopressin (AVP) is a 9 amino acid peptide with a 6-member disulfide ring. It is structurally related to oxytocin differing in 2 amino acids. It is synthesized in the hypothalamus supraoptic and paraventricular nuclei. It is stored in the posterior pituitary for release. AVP has powerful antidiuretic action and is also known as antidiuretic hormone (ADH). It acts upon the collecting tubule of the kidney increasing permeability to water and urea. It also has neurotransmitter and peripheral humoral functions.

AVP has been shown to be released upon both osmotic and non-osmotic stimuli, and its release into peripheral blood causes effects upon a number of factors, including emotional stress, posture, blood volume, and temperature. Alcohol appears to inhibit AVP secretion. Serum AVP measurement is used clinically for studies involving diabetes insipidus, syndrome of inappropriate ADH secretion (SIADH), ectopic AVP production and pyschogenic water intoxication.