Ghrelin, a novel 28—amino acid orexigenic peptide discovered in 1999, has given us further insights into the control of energy homeostasis and growth hormone secretion. As a natural endogenous ligand of the growth hormone secretagogue receptor, it potently stimulates growth hormone release but is also implicated in many other homeostatic mechanisms. Released from the stomach, it stimulates lactotroph and corticotroph secretion, increases appetite and adiposity, has beneficial hemodynamic effects, has prokinetic and gastric acid secretory functions in the stomach, and may even be implicated in sleep. As advances in the understanding of appetite and obesity are made, it is timely to review the possibly central role of ghrelin in these physiological and pathophysiological states. This review will discuss the recent literature concerning this exciting novel neuropeptide and discuss the possible therapeutic possibilities it may open up to us.