We studied the effects of tranilast, an anti-allergic and anti-proliferative drug in clinical use, on VEGF/VPF-induced vascular permeability in a rat air pouch model. A large increase in vascular permeability was induced by injection of 4 ml of a 100 ng/ml VEGF/VPF solution into the preformed air pouch. Over a 15-min period, tranilast inhibited the VEGF/VPF-induced vascular permeability in a dose-dependent manner. This result suggests that tranilast, which we recently found to inhibit VEGF/VPF-induced angiogenesis, could also improve VEGF/VPF-dependent increases in vascular permeability.