The delivery of drugs into the central nervous system (CNS) is greatly hindered by the blood-brain barrier (BBB) and the blood-CSF barrier (BCSFB). Emerging evidence suggests that uptake and efflux transporters expressed at these CNS barriers are an important determinant of brain exposure and CNS activity or toxicity of many drugs and neuroactive agents. This symposium will highlight recent advancement in our understanding of the mechanisms, regulation and in vivo significance of ABC and SLC transporters at the BBB and BCSFB.