Two species of parasite copepoda, Caligus minimus and Lernanthropus kroyerii have been found to have the intestine covered by an epithelium of absorbent cells, synthesis cells and digestive or bioaccumulative cells. On the posterior tract another cellular type is found, although it is less frequent. These cells measure about 10μm in height and they differ from others in their clear hyaloplasm and their high nucleo-cytoplasmatic ratio. The granular endoplasmatic reticulum and the Golgi complex show different development degree in the different cell types, and they give rise to secretion granules which characterize these cells. The granules show a great diversity in shape, electron density and size (from 50 to 100 nm) in the different cells. These results allow us to define the existence of endocrine cells in the intestine of copepoda, similar to the ones we find in the gastrointestinal system of mammals and various invertebrate groups. Presumably, these cells are involved in the regulation of digestive processes in the rest of cellular elements which make up the intestinal tract, releasing intracellular proteins by means of exocytosis discontinuous processes.