Canadian scientists have played a major role in the discovery and characterization of various atrial natriuretic factors (ANF). It is now clear that this family of polypeptides induces multiple biological actions in a broad variety of peripheral tissues including the kidney, adrenal gland, and blood vessels. One generalized observation derived from multiple studies reveals that these peptides most likely act as important modulators of homeostasis by modulating the production of various body fluids. Recently, it became clear that the atrial natriuretic factors present in the central nervous system could influence various brain functions. Thus, the ANF-like peptides should be considered as a new family of brain–heart peptides.The present symposium, the first of its kind, was organized to examine and critically discuss the evidence for putative roles of atrial natriuretic peptides in the brain. It was clearly demonstrated that atrial natriuretic peptide-like immunoreactivity is widely distributed in mammalian and nonmammalian brains with a high number of cell bodies and (or) fiber terminals present in areas associated with water and salt intake and with the control of cardiovascular parameters. The gene transcripts responsible for the production of brain atrial natriuretic polypeptides have been isolated and their characteristics appear to be similar to those found in peripheral tissues. The presence and plasticity of specific brain ANF receptor sites have also been reported. It appears that at least one population of sites is associated with the activation of guanylate cyclase and it was also shown that specific ANF receptors are located on brain microvessels and can modulate the permeability of the blood-brain barrier. Finally, it has been shown that atrial natriuretic polypeptides exert various biological actions in the brain including electrophysiological effects in the hypothalamus, modulation of water and salt intake, alteration of various cardiovascular parameters, and release of certain pituitary hormones.Interactions with dopaminergic pathways, vasopressin, and (or) angiotensin II systems could be associated with some biological effects of atrial natriuretic peptides in the brain. Naturally, much remains to be known on the exact physiological role of brain atrial natriuretic factors, but this meeting represents the first attempt towards the integration of the most recent findings in this exciting research area.This symposium was an official satellite of the first joint meeting of the International Society for Neurochemistry and the American Society for Neurochemistry, held in Venezuela in May–June 1987. The success of the symposium has been ensured by generous donations from the International Society for Neurochemistry, the Medical Research Council of Canada, and various companies including Amersham International (England), ANAWA Trading SA (Switzerland), Ayerst Laboratories (U.S.A.), Bachem (Switzerland), Bayer AG (West Germany), Bio-Mega Inc. (Canada), Ciba-Geigy Corporation (U.S.A.), Dupont Canada – New England Nuclear Co. (Canada), Eli Lilly Research Laboratories (U.S.A.), Farmitalia Carlo Erba (Italy), Institut Henri Beaufour (France), Merck Sharp &Dohme Research Laboratories (U.S.A.), Miles Laboratories Inc. (U.S.A.), Monsanto Co. (U.S.A.), Novabiochem (Switzerland), Novopharm Ltd. (Canada), Peninsula Laboratories (U.S.A.), and the Peptide Institute and Protein Research Foundation (Japan).