Objective To investigate the intrapulmonary expression of tumor necrosis factor-? (TNF-?) gene during acute pancreatitis, as well as correlation between TNF-? and lung injury seen in many patients undergoing acute necrotizing pancreatitis (ANP). Methods Ninety SD rats were divided into three groups randomly. Acute edematous pancreatitis(AEP) and ANP were induced by retrograde infusion of sodium taurocholate (0.5% and 5%) into biliopancreatic duct respectively. Animals in the last group only underwent sham-operation. All the animals were sacrificed at certain time, plasma level of amylase and TNF-? was assessed. Intrapulmonary expression of TNF-? mRNA and TNF-? protein was detected by semi-quantitative RT-PCR and immunohisto- chemistry. Cell apoptosis was assessed by TUNEL method. Results Intrapulmonary expression of TNF-? mRNA was much stronger and more sustained in ANP group than that in AEP group (P