Before the introduction of DDA VP, centrnl diabetes insipidus was treated by the administration of a more or less purified extract from bovine or porcine posterior pituitaries, and the prepamtions were mostly given in the form of nasal snuff. In 1956, the structure of vasopressin became known and two forms were found, namely arginine vasopressin (A VP) in humans and most other species, and lysine vasopressin (L VP) which was found in the pig. In 1967, Zaornl et al. were the frrst to synthesize l-desamino-8-D-arginine vasopressin, DDA VP. In comparison with the compounds which were previously available, DDA VP offered increased antidiuretic potency and an equally distinct shift of the antidiuretic to pressor potency rntio. As a result of the pioneering studies of Cash and Mannucci, numerous publications appeared in the medical literature of the 80's, widening the fields of clinical application of the drug. A very important aspect of this drug is that it can be used as an alternative treatment for mild factor VllI deficiencies, mild hemophilia A and von Willebrnnd's disease. These congenital deficiencies are far from mre and have, up to now, been treated with plasma-derived factor VIII concentrates; in the countries in which desmopressin has not been used a consistent proportion of these patients have seroconverted for HIV 1 and hepatitis.