There is a growing body of experimental and clinical evidence to indicate that stress influences gastrointestinal motility. The most common pattern of gastrointestinal motor alterations induced by a variety of different stress factors is that of delayed gastric emptying and accelerated colonic transit. Central administration of corticotrophin releasing factor mimics both of these effects. This review focuses on the effects of two centrally acting peptides known to influence gastrointestinal motility and transit in experimental animals: thyrotrophin releasing hormone and corticotrophin releasing factor. The biological actions of these peptides are discussed in relation to the motility changes and pathways involved in their actions.