In a review of arteriograms of 72 unselected consecutive cases of pancreatitis, seven patients were found to have arterial aneurysms involving branches of the peripancreatic vessels. During the same period, arteriograms of 84 cases of carcinoma of the pancreas were reviewed and no aneurysms of any of these vessels were found. The demonstration of aneurysms of the peripancreatic arteries in pancreatitis is an important differential feature from carcinoma of the pancreas. Both carcinoma of the pancreas and chronic pancreatitis can cause encasement of the arterial vessels and obstruction of the splenic or the superior mesenteric vein, therefore resulting in a similar angiographic appearance. Thus an aneurysm seen in such a patient is a helpful distinguishing feature. In addition, these aneurysms are an important source of hemorrhage and mortality in pancreatitis.