Objective:To investigate the effect of dexamethasone(Dx) combined with modified Dachengqi Decoction(大承气汤,DCQD),a Chinese herbal decoction for purgation,on patients with severe acute pancreatitis(SAP) accompanied with systematic inflammatory response syndrome(SIRS).Methods:A total of 81 patients diagnosed as SAP were randomly assigned to a control group or treatment group according to a random number table generated from an SPSS software.The patients in the control group(38 cases) received standard treatment and Chinese herbal decoction for purgation;those in the treatment group(43 cases) received additional 1 mg/(kg·d) dexamethasone(Dx) treatment for three days based on the above treatment.The mortality rate,acute respiratory distress syndrome(ARDS),renal failure,hemorrhage,sepsis,pancreatic pseudocyst, pancreatic abscess,operability,and days of hospitalization were compared between the two groups.Results: Three patients in the control group and eight patients in the treatment group dropped out from the study with a drop-out rate of 7.8%and 18.6%,respectively,and no statistics difference was shown between the two groups (P>0.05).Dx treatment significantly reduced ARDS rate and shortened the length of hospitalization compared to those in the control group(7/35,20.0%versus 15/35,42.9%,P=0.0394;32.5±13.2 days versus 40.2±17.5 days,P=0.0344).Other parameters including the mortality rate were not significant different between the two groups.Conclusion:Dx combined with DCQD could decrease the risk of developing ARDS in SAP patients with SIRS and shorten their length of hospitalization. Objective: To investigate the effect of dexamethasone (Dx) combined with modified Dachengqi Decoction (aQQQ), a Chinese herbal decoction for purgation, on patients with severe acute pancreatitis (SAP) accompanied by systemic inflammatory response syndrome (SIRS) A total of 81 patients diagnosed as SAP were randomly assigned to a control group or treatment group according to a random number table generated from an SPSS software.The patients in the control group (38 cases) received standard treatment and Chinese herbal decoction for purgation; those in the treatment group (43 cases) received additional 1 mg / (kg · d) dexamethasone (Dx) treatment for three days based on the above treatment.The mortality rate, acute respiratory distress syndrome (ARDS), renal failure , hemorrhage, sepsis, pancreatic pseudocyst, pancreatic abscess, operability, and days of hospitalization were compared between the two groups. Results: Three patients in the control group and eight patients in the treatment group dropped out from the study with a drop-out rate of 7.8% and 18.6%, respectively, and no statistics difference was shown between the two groups (P> 0.05) .Dx treatment significantly reduced ARDS rate and shortened the length of hospitalization to those in the control group (7/35, 20.0% versus 15/35, 42.9%, P = 0.0394; 32.5 ± 13.2 days versus 40.2 ± 17.5 days, P = 0.0344) .Other parameters including the mortality rate were not significant different between the two groups. Conclusion: Dx combined with DCQD could decrease the risk of developing ARDS in SAP patients with SIRS and shorten their length of hospitalization.