Ghrelin is a 28-amino acid acylated peptide predominantly produced by the stomach. It displays strong GH-releasing activity mediated by the hypothalamus-pituitary GH secretagogue (GHS)-receptors specific for synthetic GHS. Ghrelin also acts on other central and peripheral receptors and enables other actions including: stimulation of lactotroph and corticotroph secretion; food-intake; gastro-entero-pancreatic functions; metabolic; cardiovascular activity; and anti-proliferative effects. This volume aims to highlight the impact and function of the hormone ghrelin and provide insight to neuroendocrinologies and researchers interested in its molecular and clinical relevance.