Growth hormone releasing hormone receptor (GHRH-R) is a family B1 G-protein coupled receptor found predominantly on pituitary somatotrophs. In the adults it is required for the normal synthesis and release of growth hormone (GH) from the pituitary. During development it is required for the normal proliferation and maturation of somatotrophs within the pituitary. Mutations of this receptor in mouse and man are associated with GH deficiency, short stature and pituitary hypoplasia. This signaling system plays important roles in growth and development, metabolism of muscle and fat, and is implicated in the regulation of cardiac and immune function, wound healing, tumor growth and the aging process. Current areas of active research discussed here include: studiesof the structure of the receptor binding site and its interaction with GHRH, alternative splice variants of the GHRH-R which appear to promote tumor proliferation, truncated receptor isoforms that act as dominant negative inhibitors of wild type receptor, and the unclear physiologic role of the GHRH system in birds and fishes.