Pseudoaneurysm is a rare life-threatening complication of chronic pancreatitis. It can be diagnosed by various imaging modalities including computerized tomography (CT), ultrasound, and angiography. Early diagnosis and radiologic or surgical treatment can promise better outcomes. However, pseudoaneurysm is not easily diagnosed. It can be misdiagnosed as a pseudocyst with secondary infection. Rarely, the correct diagnosis is made by an inadvertent trial with percutaneous drainage. The endoscopically identified hemosuccus pancreaticus is also a rare finding. Recently, we experienced two cases of pseudoaneurysm in patients with chronic pancreatitis. They did not have any evidence of bleeding in the initial eddoscopy or evidence of pseudoaneurysms in the initial ultrasound and CT scan. In one case, the pseudoaneurysm was identified during a percutaneous drainage procedure, performed to diagnose and manage a cystic lesion which apperared to be an infected cyst. In the other case, the pseudoaneurysm was suspected after the hemosuccus pancreaticus was found during endoscopy performed due to recurrent hematemesis. Both cases were successfully treated with arterial embolization of the pseudoaneurysms. (Korean J Gastrointest Endosc 2001;23:263-268)