Acute pancreatitis is an inflammatory disease of the pancreas associated with high mortality but without a specific therapy. Intrapancreatic protease activation appears to be an early event in the development of acute pancreatitis but its association with pathogenesis has not been established. Recently it has been demonstrated that an enormous rise in the cytoplasmic Ca2+ levels of pancreatic acinar cells could be associated with the development of acute pancreatitis, thereby suggesting that Ca2+ channel could be a potential target for treatment. In this study, the protective effects of calcium channel blockers such as 2-aminoethoxydiphenyl borate, dantrolene and verapamil were investigated in cerulein-induced acute pancreatitis in vivo. Rats were divided into five groups. Group 1 (control), group 2 (cerulein, 100 mu g/kg), group 3 (cerulein+2-aminoethoxydiphenyl borate, mg/kg), group 4 (cerulein+dantrolene, 10 mg/kg) and group 5 (cerulein+verapamil, 2.5 mg/kg). Activities of amylase, lipase, cathepsin B, pancreatic secretory trypsin inhibitor, trypsin, levels of trypsinogen activation peptide and trypsinogen were measured addition to histological examination of the sections of pancreas. The results showed that cerulein increased the amylase, lipase and trypsin activities and trypsinogen activation peptide levels significantly. Administration of calcium channel blockers significantly protected the pancreas from histological damage (p<0.05). The results of this study demonstrated that calcium channel blockers can mitigate early protease activation and pancreas injury. It was suggested regulation of calcium channels would be relevant to maintain pancreatic acinar cell homeostasis and further research is necessary to understand the protective effects of calcium channel blockers.