<jats:p>Background: Hydrogen sulfide (H2S), known as the third endogenous gaseous transmitter, has received increasing attention because of its diverse effects, including angiogenesis, vascular relaxation and myocardial protection.We aimed to investigate the role of H2S in oxidative/nitrative stress and inflammation in acute lung injury (ALI) induced by endotoxemia. Methods: Male ICR mice were divided in six groups: (1) Control group; (2) GYY4137treatment group; (3) L-NAME treatment group; (4) lipopolysaccharide (LPS) treatment group; (5) LPS with GYY4137 treatment group; and (6) LPS with L-NAME treatment group. The lungs were analysed by histology, NO production in the mouse lungs determined by modified Griess (Sigma-Aldrich) reaction, cytokine levels utilizing commercialkits, and protein abundance by Western blotting. Results: GYY4137, a slowly-releasing H2S donor, improved the histopathological changes in the lungs of endotoxemic mice. Treatment with NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, increased anti-oxidant biomarkers such as thetotal antioxidant capacity (T-AOC) and theactivities of catalase (CAT) and superoxide dismutase (SOD) but decreased a marker of peroxynitrite (ONOO-) action and 3-nitrotyrosine (3-NT) in endotoxemic lung. L-NAME administration also suppressed inflammation in endotoxemic lung, as evidenced by the decreased pulmonary levels of interleukin (IL)-6, IL-8, and myeloperoxidase (MPO) and the increased level of anti-inflammatory cytokine IL-10. GYY4137 treatment reversed endotoxin-induced oxidative/nitrative stress, as evidenced by a decrease in malondialdehyde (MDA), hydrogenperoxide (H2O2) and 3-NT and an increase in the antioxidant biomarker ratio of reduced/oxidized glutathione(GSH/GSSG ratio) and T-AOC, CAT and SOD activity. GYY4137 also attenuated endotoxin-induced lung inflammation. Moreover, treatment with GYY4137 inhibited inducible NOS (iNOS) expression and nitric oxide (NO) production in the endotoxemia lung. Conclusions: GYY4137 conferred protection against acute endotoxemia-associated lung injury, which may have beendue to the anti-oxidant, anti-nitrative and anti-inflammatory properties of GYY4137. The present findings warrant further exploration of the clinical applicability of H2S in the prevention and treatment of ALI.</jats:p>