Originally thought of as a stomach-derived endocrine peptide acting via its receptors in the CNS to stimulate food intake and GH expression, ghrelin and its receptor, GHS-R, are widely expressed across a number of organ systems, including cancer cells. However, evidence for a direct functional role of ghrelin and its receptor in tumors of CNS origin remains to be defined. Here we demonstrate that human astrocytoma cell lines, U-118, U-87, CCFSTTG1 and SW1008, express 6-, 11-, 15- and 29-fold higher GHS-R expression compared to primary normal human astrocytes. The ligation of GHS-R by ghrelin on these cells results in an increase in intracellular calcium mobilization, PKC activation, actin polymerization, MMP2 activity and astrocytoma motility. In addition, ghrelin led to actin polymerization and membrane ruffling on cells with the specific co-localization of the small GTPase, Rac1, with GHS-R on the leading edge of the astrocytoma cells and imparting the tumor cells with a motile phenotype. Disruption of endogenous ghrelin-GHS-R pathway by RNAi results in diminished motility, MMP activity and Rac expression while tumor cells stably overexpressing GHS-R exhibited increased cellular motility. The relevance of ghrelin and GHS-R expression was verified in clinically relevant tissues from 20 patients with oligodendroglioma (ODG), grade II, III and grade IV astrocytomas. Analysis of CNS tumor tissue microarray revealed that strong GHS-R and ghrelin expression was significantly more common in high grade tumors as compared to low grade ones. Together, these findings suggest a novel role for the ghrelin-GHS-R axis in astrocytoma cell migration and invasiveness of cancers of CNS origin.