Growth-hormone-releasing hormone (GHRH, somatoliberin) is the hypothalamic peptide hormone that specifically stimulates synthesis and release of growth hormone (GH, somatotropin) by somatotrope cells of the anterior pituitary gland. GHRH is the last of the classically postulated hypothalamic hormones to be characterized, synthesized, and used in clinical medicine. In this review of GHRH, I discuss the discovery and characterization of the peptide, its role in the regulation of GH secretion, and its clinical use in pathological states of GH excess and GH deficiency. The two most clinically useful aspects of GHRH are to establish the etiology of GH deficiency, most commonly the result of a hypothalamic GHRH deficiency, and to treat GH-deficient children. Use of GHRH as therapy for GH deficiency currently is experimental and, to date, results encourage the idea of a therapeutic role for this peptide in promoting endogenous GH secretion with resulting acceleration of linear growth.