Tissue specimens of the normal pancreata from three adult patients were subjected to serial sectioning and computer-assisted three-dimensional reconstruction of the lobules, blood vessels, pancreatic ducts, and islets, to establish the anatomical relation among these structures. Most lobules, although more or less imperfectly demarcated by septa, were found to receive a single duct (lobular duct), justifying their definition as “glandular lobules.” However, there were also lobules receiving not only a lobular duct of their own but a small accessory duct from a neighboring lobule. On the other hand, these lobules were shown not to correspond to the territories of arterial supply, leaving no ground for defining them as “vascular lobules.”