Effects of different closes of dexamethasone plus flunixin meglumine on survival rate were investigated in lethal endotoxemia. A total of 60 Balb/C female mice were divided into 4 equal groups. Lethal endotoxemia (80-100%) was induced by lipopolysaccharide injection (Group 1, 1 mg, intraperinoneally). At 4 hours after the lipopolysaccharide injection; low-dose dexamethasone (0.6 mg/kg, SID, 5 days, intramuscularly) + flunixin meglumine (2 mg/kg, SID, 5 days, subcutaneously), normal-dose dexamethasone (2 mg/kg, SID, 5 days, intramuscularly) + flunixin meglumine (2 mg/kg, SID, 5 days, subcutaneously) and high-dose dexamethasone (10 mg/kg, SID, 5 days, intramuscularly) + flunixin meglumine (2 mg/kg, SID, 5 days, subcutaneously) were injected to Group 2, 3 and 4, respectively. After the injections, survival was monitored at 7 days and 13.3%, 13.3%, 33.3% and 73.3% survival rates were observed in Groups 1, 2, 3 and 4, respectively. As results, high-dose dexamethasone plus flunixin meglumine may be the treatment of choice for endotoxaemia in animals.