AIM: To study the influence and mechanisms of dexamethasone on mesenteric lymph node of rats with severe acute pancreatitis (SAP). METHODS: The SAP rats were assigned to model, treated or sham-operated groups. The mortality, pathological changes of mesenteric lymph nodes, expression levels of NF-kB, P-selectin, Bax, Bcl-2 and caspase-3 protein and changes in apoptotic indexes in lymph nodes were observed at 3, 6 and 12 h after operation. The blood levels of endotoxin, superoxide dismutase (SOD), malondialdehyde (MDA), and endothelin-1 (ET-1) in blood were determined. RESULTS: SOD content, expression of Bax protein and apoptotic index were significantly higher in the treated group than in the model group at different time points (P < 0.05 or P < 0.01). Other blood-detecting indexes and histopathological scores of mesenteric lymphnodes were lower in the treated than in the model group (P < 0.05, P < 0.01 or P < 0.01). NF-kB protein expression was negative in all groups. Comparing P-selectin and caspase-3 expression levels among all three groups, there was no marked difference between the model and treated group. CONCLUSION: Dexamethasone can protect mesen-teric lymph nodes. The mechanism may be by reducing the content of inflammatory mediators in the blood and inducing lymphocyte apoptosis. AIM: To study the influence and mechanisms of dexamethasone on mesenteric lymph node of rats with severe acute pancreatitis (SAP). METHODS: The SAP rats were assigned to model, treated or sham-operated groups. The mortality, pathological changes of mesenteric lymph nodes , expression levels of NF-kB, P-selectin, Bax, Bcl-2 and caspase-3 protein and changes in apoptotic indexes in lymph nodes were observed at 3, 6 and 12 h after operation. The blood levels of endotoxin, superoxide dismutase (SOD), malondialdehyde (MDA), and endothelin-1 (ET-1) in blood were determined. RESULTS: SOD content, expression of Bax protein and apoptotic index were significantly higher in the treated group than in the model group at different time (P <0.05 or P <0.01). Other blood-detecting indexes and histopathological scores of mesenteric lymphnodes were lower in the treated than in the model group (P <0.05, P <0.01 or P <0.01) expression was negative in all groups. Comparing P-selec tin and caspase-3 expression levels among all three groups, there was no marked difference between the model and treated group. CONCLUSION: Dexamethasone can protect mesen-teric lymph nodes. The mechanism may be by reducing the content of inflammatory mediators in the blood and inducing lymphocyte apoptosis