Pancreatic polypeptide (PP) immunoreactivity was demonstrated in the endocrine pancreas of the anglerfish (Lophius americanus) and the channel catfish (Ictalurus punctatus) using immunohistochemistry. In both species, PP-immunoreactive cells were localized at the periphery of endocrine tissue. In Lophius americanus, PP-immunoreactivity could be localized in the principal islet, the pyloric or secondary islet, and the mesenteric or tertiary islets. A peripheral localization of PP-immunoreactive cells having characteristic angular, or dendritic, appearance demonstrated in the above two species are a common finding among many teleost species. This peripheral localization of cells, particularly in principal (splenic) anglerfish islets, make them an ideal source of islet tissue which can be easily enriched or depleted of pancreatic polypeptide-containing cells for use in studying the synthesis and secretion of islet hormones.