Emerging data have provided evidence for the presence of a local renin-angiotensin system (RAS) in the pancreas, which play a role in the regulation of pancreatic microcirculation, thus affecting islet hormonal secretion. The present study aimed, therefore, at elucidating the presence and changes of angiotensin-converting enzyme (ACE) using reverse transcription-polymerase chain reaction (RT-PCR) and a specific assay for ACE activity using the internally quenched fluorogenic substrate Meoc-DL-Amp-Gly-Lys(epsilon -DNP)-Gln-OH. RT-PCR clearly demonstrated the expression of ACE mRNA in the pancreas. ACE activity was markedly and significantly increased by chronic hypoxia and by acute pancreatitis when compared with that of their respective control pancreas. Addition of captopril, a specific inhibitor for ACE, completely blocked the ACE activity both in the control and experimental groups. All these data suggest that increased activity of pancreatic ACE in chronic hypoxia and acute pancreatitis could have implications for pancreatic physiology and pathophysiology.