Isoflurane prevents increased alveolar–capillary barrier permeability following injury with lipopolysaccharide and mechanical ventilation. C57BL/6 mice were subjected to injury with nebulized lipopolysaccharide (LPS) and mechanical ventilation to induce ventilator-induced lung injury (LPS/VILI) or nebulized phosphate-buffered saline followed by mechanical ventilation (PBS/VILI) before performing bronchoalveolar lavage (BAL). (A) BAL protein increased significantly following LPS/VILI (n = 3) compared with PBS/VILI (n = 3). Isoflurane treatment following LPS but before VILI (n = 4) prevented the increase in BAL protein seen with LPS/VILI without isoflurane (n = 3) (*P < 0.001 vs. LPS/VILI and no isoflurane by two-way ANOVA with Bonferroni posttest). In a separate experiment, mice were subjected to LPS/VILI with isoflurane (n = 6) or control gas (n = 5). Mice treated with isoflurane had significantly less alveolar–capillary permeability as measured by Evan blue assay (B) and wet to dry ratio (C). **P < 0.05 versus LPS/VILI and no isoflurane by Mann–Whitney test.