The aim of this study was to examine whether administration of valproic acid (VPA), a histone deacetylase inhibitor, inhibits proinflammatory mediators and ameliorate visceral vasopermeability both in a rat model of major burn, and also in rat cultured endothelial cells stimulated with permeability evoking mediators. SD rats were subjected to a 50% TBSA full-thickness scald injury, and treated with either saline or VPA (300 mg/kg) intraperitoneally. Pulmonary vascular endothelial growth factor (VEGF), myeloperoxidase (MPO), pulmonary microvascular permeability, water content, and acetylation of histone H3K9 of lungs were evaluated. In addition, pulmonary microvascular endothelial cells (PMECs) from male SD rats were cultured. With then, MPO, VEGF, histone acetylation, and the permeability of PMECs were investigated. Lethal scald injury resulted in a significant increase in microvascular permeability and water content of lung, accompanied by a significant elevation of the content of VEGF and activity of MPO, and a decrease of histone acetylation. VPA treatment significantly alleviated the microvascular permeability and water content of lung, lowered the levels of VEGF and MPO, and promoted acetylation of histone H3K9 following scald injury. Moreover, VPA reduced permeability of monolayer PMECs subjected to scald serum challenge, reduced the level of MPO and VEGF in supernatants, and promoted acetylation of histone H3K9 in PMECs. These results indicated that VPA can protect pulmonary microvascular endothelial barrier, alleviate proinflammatory mediators-evoked vascular hyperpermeability and tissue edema and improve the survival rate of rats subjected to lethal scald injury.