Objective To deter mine the protective effect of ulinastain(UTI) on multiple organ dysfunction syndrome (MODS). Methods Sheep models of MODS were induced by lipopolysaccharide(LPS). The animals were randomly divided into four groups: normal control group, MODS group, UTI treatment groupⅠand groupⅡ. The anaesthetized animals received intravenous infusion of LPS (6μg / kg) to induce MODS in MODS group and UTI treatment groups. The animals received intravenous injection of UTI (30000 U/kg) for 3 days, once daily in UTI treatment groupⅠand twice daily in groupⅡ. Arterial oxygen pressure(PaO2) was measured at 0(basement), 1, 2, 3, 6 and 12h respectively. Blood samples were taken for determination of serum alanine aminotransferase(ALT), aspartate aminotransferase (AST), creatinine(Cr), total bilirubin(TBIL) and blood routine at 0(basement), 3,6,12,24,48 and 72h respectively. Results PaO2 decreased as early as at 1 hour after injection of LPS. Compared with MODS group, PaO2 decreased less significantly in UTI treatment group. AST, ALT, TBIL and Cr in UTI treatment groups were significantly lower than those in MODS group(P <0.05), but there was no obvious difference between UTI treatment groupⅠ and groupⅡ. The animal mortality was 66.6%, 50.0 % and 33.3% in MODS group, UTI treatment groupⅠand groupⅡ respectively. Conclusion Prophylactic application of UTI could reduce the mortality of MODS animals induced by LPS. It has protective effects on lung, kidney and liver injuries in MODS animals.