Recent studies from our laboratory demonstrated the involvement of endothelial cell reactive oxygen species (ROS) formation and activation of apoptotic signaling in vascular hyperpermeability following hemorrhagic shock (HS). The objective of this study was to determine if (-)-deprenyl, an antioxidant with anti-apoptotic properties would attenuate HS-induced vascular hyperpermeability. In rats, HS was induced by withdrawing blood to reduce the MAP to 40 mmHg for 60 minutes followed by resuscitation for 60 minutes. To study hyperpermeability, the rats were injected with FITC-albumin (50 mg/kg) and the changes in integrated optical intensity of the mesenteric postcapillary venules were obtained intra and extra vascularly utilizing intravital microscopy. Mitochondrial ROS formation and mitochondrial transmembrane potential (ΔΨm) were studied using dihydrorhodamine 123 and JC-1 respectively. Mitochondrial release of cytochrome c was determined using ELISA and caspase-3 activity by a fluorometric assay. Parallel studies were performed in rat lung microvascular endothelial cells (RLMEC) utilizing pro-apoptotic BAK as inducer of hyperpermeability. Hemorrhagic shock induced vascular hyperpermeability, mitochondrial ROS formation, decrease in ΔΨm, release of cytochrome c and caspase-3 activation (p < 0.05). (-)-Deprenyl (0.15 mg/Kg) attenuated all these effects (p < 0.05). Similarly in RLMEC, (-)-deprenyl attenuated BAK peptide induced monolayer hyperpermeability (p < 0.05), ROS formation, decrease in ΔΨm, cytochrome c release (p < 0.05) and activation of caspase-3 (p < 0.05). The protective effects of (-)-deprenyl on vascular barrier functions may be due to its protective effects on ΔΨm thereby preventing mitochondrial release of cytochrome c and caspase-3 mediated disruption of endothelial adherens junctions.