Elevated levels of chemokines have been observed in various diseases of the CNS. Little is known, however, about how these chemokines affect parenchymal cells of the CNS. The current studies examine astrocyte chemotaxis to the mouse chemokine macrophage inflammatory protein-1 (MIP-1a). Murine astrocytes demonstrate directed migration along a chemical gradient in response to 10e-10 – 10e-8M MIP-1a. Peak chemotactic responses are noted at 1e-09M. MIP-1a-induced astrocyte migration is specifically inhibitable with pertussis toxin, suggesting a role for G1a proteins in the signaling process. RT-PCR and insitu hybridization were used to identify expression of the murine CCR1MIP-1a receptor on astrocytes. Astrocytes contain mRNA for CCR1, but messages for CCR4 and the orphan chemokine receptorMIP-1aR-like #1 were not detected. The combined results suggest that a functional chemokine receptor is expressed on resident cells of the CNS. We speculate that the interactions of chemokines with astrocytes are involved in inflammatory reactions of the CNS.