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.