Pancreatic apudomas are not common but are frequently curable. Thus, it is important for every clinician to be fully aware of the varied clinical syndromes that suggest their presence. The availability of specific radioimmunoassays has made confirmation of the diagnosis relatively simple. Advances in the techniques for staining the different cell types have led to the recognition that many of these tumors are mixed, and that the general term "pancreatic apudoma" is appropriate. Pancreatic endocrine tumors, as examples to "nature's experiments," have yielded considerable insight into the possible physiologic effects of the various peptides they produce. It is to be hoped that further study of tumors such as the somatostatinoma and PPoma may yield further information about these enigmatic compounds.