The relationship between intracelluar trypsinogen activation and NF-r,B activation in rat pancreatic acinar cells induced by M3 cholinergic receptor agonist (carbachoi) hyperstimulation was studied. Rat pancreatic acinar cells were isolated, cultured and treated with carbachol, the active pro- tease inhibitor (pefabloc) and NF-кB inhibitor (PDTC) in vitro. Intracelluar trypsin activity was measured by using a fluorogenie substrate. The activity of NF-кB was monitored by using electro- phoretic mobility shift assay. The results showed that after pretreatment with 2 mmol/L pefabloc, the activities of trypsin and NF-кB in pancreatic acinar cells treated with high concertrations of carbachol (10-3 mol/L) in vitro was significantly decreased as compared with control group (P＜0.01). The addi- tion of 10-2mol/L PDTC resulted in a significant decrease of NF-кB activities in pancreatic acinar cells after treated with high concertrations of carbachol (10-3 mol/L) in vitro, but the intracelluar trypsinogen activity was not obviously inhibited (P＞0.05). It was concluded that intracelluar trypsi- nogen activation is likely involved in the regulation of high concertrations of carbachol-induced NF-кB activation in pancreatic acinar cells in vitro. NF-кB activation is likely not necessary for high concertrations of carbachol-induced trypsinogen activation in pancreatic acinar cells in vitro.