Objective To investigate lipopolysaccharide (LPS) stimulates the expression of nuclear factor-KB (NF-κB) mRNA and tumor necrosis factor-a( TNF-α) mRNA in rat's pancreatic acinus AR42J cell line, and further address the pathogenesis of acute pancreatitis. Method The AR42J cell line was stimulated with different concentrations of LPS (0.001, 0.01, 0.1, 1.0, 10 and 100 mg/L) for 18 hours, or stimulated with 10 mg/L of LPS for different lengths of time (2, 6, 12,18 and 24 hrs) .Then, the expressions of NF-κB-P65 mRNA and TNF-α mRNA were determined by using RT-PCR, the levels of TNF-α protein in the culture supernatant were measured with radio-immuno assay (RIA), and the correlation between the expressions of TNF-α mRNA and NF-κB mRNA was analyzed. Results Both the expressions of NF-κB mRNA and TNF-α mRNA were up-regulated when AR42J cell line was stimulated with 10 mg/L of LPS for 2 hours or with 0.001 mg/L of LPS for 18 hours in both dose-dependent and time-dependent manners. Similarly, the levels of TNF-α protein were up-regulated when AR42J cell line was stimulated with 0.01 mg/L of LPS for 18 hours or with 10 mg/L of LPS for 6 hours in both dose-dependent and time-dependent manners. Statistical analysis revealed the positive correlation between the expressions of TNF-α mRNA and NF-κB-P65 mRNA(r = 0.962, P < 0.01). Conclusions LPS stimulates the expressions of TNF-α mRNA and NF-κB mRNA in both dose-dependent and time-dependent manners, and their expressions are closely correlated, suggesting the inhibition of their expressions as a potential therapeutic target for acute panceatitis.