Objective: To investigate the effects of levosimendan(LS) combined with arginine vasopressin(AVP) on sepsis-induced lung injury(ALI) in swine. Methods: Fourteen female pigs were anesthetized and mechanically ventilated,and then peritonitis model was established. When mean arterial pressure (MAP) decreased to less than 60 mmHg,animals were randomly assigned to two groups: norepinephrine (NE) or LS (fixed dose of 0.4 -滋g/kg/min) + AVP (fixed dose of 0.57 mU/kg/min). If necessary,NE was titrated to maintain MAP between 65 and 75 mmHg in both groups. MAP,mean pulmonary artery pressure (MPAP),pulmonary capillary wedge pressure(PCWP),atrial oxygen saturation (SaO2),mixed venous saturation (SvO2),lactate concentration,hemoglobin concentration (Hb),cardiac output (CO),and plasma levels of TNF--琢,IL-6,IL-10,and NOax were determined at the following time points:before the establishment of sepsis model (baseline,T1),shock time(T2),and 6 h(T3) and 12 h(T4) after shock. Qs/Qt(venous admixture) was calculated at these time points. Time to the onset of septic shock point,total NE and fluid requirements were also recorded. Lung was removed for the determinations of pulmonary wet-to-dry ratio(W/D),myeloperoxidase activity (MPO),histological changes and apoptotic cells. Results: MAP,PCWP,time to the onset of septic shock point,total fluid requirements and Hb had no significant differences between the two groups(P > 0.05). Compared with NE group,MPAP,Qs/Qt,lactate concentrations,plasma levels of IL-6,and NOax at T4 and plasma levels of TNF--琢,HR and CO at T3 were significantly lower,while SaO2 and SvO2 were higher in LS+AVP group(P < 0.05). Total NE requirements,lung tissue levels of MPO activity,W/D ratio,total histological scores,and positive apoptotic cells were significantly lower in the LS+AVP group than those in NE group (P < 0.05). Conclusion: Combined LS with AVP improves gas exchange,decreases MPAP and lung inflammatory responses when compared with NE infusion alone in a porcine model of sepsis-induced ALI.