AIM: To investigate the effects of rhubarb on severe acute pancreatitis (SAP) in rats.METHODS: Severe acute pancreatitis was induced by two intraperitoneal injections of cerulein (40 μg/kg body weight) plus 5-h restraint water-immersion stress. Rhubarb (75-150 mg/kg) was orally fed before the first cerulein injection.The degree of pancreatic edema, serum amylase level,local pancreatic blood flow (PBF), and histological alterations were investigated. The effects of rhubarb on pancreatic exocrine secretion in this model were evaluated by comparing with those of somatostatin.RESULTS: In the Cerulein+Stress group, severe edema and diffuse hemorrhage in the pancreas were observed,the pancreatic wet weight (11.60±0.61 g/Kg) and serum amylase (458 490±43 100 U/L) were markedly increased (P＜0.01 vs control). In the rhubarb (150 mg/kg) treated rats, necrosis and polymorphonuclear neutrophil (PMN) infiltration in the pancreas were significantly reduced (P＜0.01), and a marked decrease (50％) in serum amylase levels was also observed (P＜0.01). PBF dropped to 38％(93±5 Ml/min per 100 g) of the control in the Cerulein+Stressgroup and partly recovered in the Cerulein+Stress+Rhubarb 150 mg group (135±12 Ml/min per 100 g) (P＜0.01). The pancreatic exocrine function was impaired in the SAP rats.The amylase levels of pancreatic juice were reduced in the rats treated with rhubarb or somatostatin, comparing with that of untreated SAP group. The bicarbonate concentration of pancreatic juice was markedly elevated only in the rhubarb treated group (P＜0.01).CONCLUSION: Rhubarb can exert protective effects on SAP, probably by inhibiting the inflammation of pancreas,improving pancreatic microcirculation, and altering exocrine secretion.