NADPase activity has been localized in the exocrine pancreas of rat, by cytochemistry according to the procedure of Smith as modified by Clermont et al. With NADP or NADPH as substrate, an intense reaction was detected in one or two intermediary saccules of the Golgi stack. Reaction product was also present in lysosomes, dense bodies and the gland lumen. It was absent from condensing vacuoles and zymogen granules. A very intense reaction was found over a "snake-like" structure not previously reported. These are elongated tubules located in basal and central portions of the acinar cell where they are frequently seen close to the Golgi stack or the basolateral cell surface.