The endothelial cells of the cerebral vasculature constitute, together with perivascular elements (astrocytes, pcricytes, basement membrane), the blood-brain barrier (BBB), which strictly limits and specifically controls the exchanges between the blood and the cerebral extracellular spacc.The existence of such a physical, enzymatic, and active barrier isolating the central nervous system has broad physiological, biological, pharmacological, and patho- logical consequences, most of which are not yet fully elucidated. The Cerebral Vascular Biology conference (CVB '95) was organized and held at the "Carre des Sciences" in Paris on July I 0-12, 1995. Like the CVB '92 conference held in Duluth, Minnesota, three years ago, the objectives were to provide a forum for presentation of the most recent progresses and to stimulate discussions in the ticld of the biology, physiology. and pathology of the blood-brain barrier. The Paris conference gathered more than !50 participants. including investigators in basic neuroscience, physicians. and stu- dents, who actively contributed to the scientific program by their oral or poster presentations. This volume contains a collection of short articles that summarize most of the new data that were presented at the conference. Six thematic parts focus on physiological transports. drug delivery, multidrug resistance P-glycoprotein, signal transduction at the BBB. interactions between the immune system and the cerebral endothelial cells, and the blood-brain barrier-related pathologies in the central nervous system. In addition, two introductory articles present new insights in the rapidly evolving topics of cerebral angiogenesis and gene transfer to the brain.