Objective:To investigate the effects of Xuebijing Injection(血必净注射液,XBJ) on survival rate and pulmonary vasopermeability in a rat model of severe scald injury.Methods:Rats were divided into two experiments:experiment 1 was monitored for 12 h post-injury for survival analysis after severe bums;in experiment 2,rats were killed for determination of pulmonary vascular permeability and pro-inflammatory mediators.In both experiments,rats were subject to third-degree 50％ total body surface area (TBSA) burns or sham injury followed by XBJ or normal saline (NS) treatment.In addition,rat pulmonary microvascular endothelium cells (PMECs) were pretreated with either XBJ or phosphate buffer saline (PBS),and then subjected to sham serum or scald serum stimulation for 2 or 6 h,followed by transwell examination for the permeability of PMECs.Meanwhile,pro-inflammatory mediators in PMECs culture supematant were also investigated.Results:The average survival time in the scald+XBJ group was 582.1 ± 21.2 min,which was significantly longer than that in the scald + NS group (345.8 ± 25.4 min,P＜0.01).Plasma levels of tumor necrosis factor-alpha (TNF-α),E-selectin,interleukin-6 (IL-6),vascular permeability and water content of lung tissues were significantly increased in animals after severe bums (P＜0.01).However,administration of XBJ significantly decreased these levels in plasma and lung tissue.In in vitro cell experiments,XBJ markedly attenuated permeability in PMECs monolayer and reduced the levels of TNF-α,IL-6 and soluble E-selectin after stimulation with scald serum (P＜0.01).Conclusions:XBJ increases early survival rate by alleviating pulmonary vasopermeability and inhibiting pro-inflammatory mediators in rats subjected to lethal scald injury.XBJ may be a potent drug in treatment of severe bums.