In the late 1960s, Said and colleagues discovered, in normal lung tissue, peptide fractions that caused potent and prolonged peripheral vasodilation and relaxed smooth muscle in vitro (Said and Mutt, 1969; Piper et al 1970); one such fraction was initially named vasoinhibitory peptide. However, much greater vasodilatory activity was found in intestinal extracts; the isolation of the active factor from porcine duodenum was undertaken in the laboratory of Viktor Mutt, and culminated in the characterization of an octacosapeptide now known as vasoactive intestinal peptide or VIP (Said and Mutt, 1972). It is now recognized that VIP is present in both peripheral and central nerve cells and is an important transmitter. It is also becoming evident that the biologically relevant structure of VIP has been highly conserved during evolution.