Ghrelin is a 28 amino acid peptide, which produces its marked effects through binding to the endogenous ligand of the growth hormone secretagogue receptor (GHS-R). Based on the contemporary literatures, it was shown that ghrelin was involved in a series of biological functions including regulation of food intake, body weight, gastrointestinal (GI) motility, hormone secretion, glucose release, cardiovascular functions, enzyme release, cell proliferation and reproduction in pigs through binding to GHS-R 1a or unidentified receptors. It was also observed that ghrelin induced adipocyte and hepatocyte proliferation of primary cultured piglet. In this paper, recent research on ghrelin structure, distribution, GHS-R receptor, biological functions and its regulatory mechanisms for pigs are presented.