The hypothalamic region of the brain in vertebrates is a center that plays an important role in feeding regulation. Many kinds of hypothalamic neuropeptides or peripheral transmitters, such as orexin, neuropeptide Y, Agouti-related peptide, melanin-concentrating hormone, proopiomelanocortin-derived peptides, galanin, galanin-like peptide, ghrelin, corticotropin releasing hormone, cholecystokinin, cocaine amphetamine-related transcript peptides and leptin, have been implicated in the regulation of feeding behavior, psychomotor activity and energy homeostasis in rodents. Recent studies have also examined the effects of these neuropeptides or factors on food intake in non-mammalian vertebrates, especially chick and goldfish, and the role of pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) in feeding behavior, locomotor activity or psychomotor activity in vertebrates. This article gives an overview of the regulation of feeding behavior and related physiology by PACAP and VIP in vertebrates in order to clarify the appetite-regulating system mediated by the two peptides.