NADPH-diaphorase activity was histochemically demonstrated in the nerve fibers, neuronal-like cell bodies and in the endothelial cells of the vasculature in the pineal gland of the turkey. The nerve fibers were localized in the choroid plexus, connecting the pineal gland with the diencephalon as well as inside the pineal gland, where they formed basket-like structures around the pineal follicles. A group of neuronal-like cell bodies was observed in the proximal part of the gland. The positive staining was not observed in the pinealocytes of rudimentary-photoreceptor type and in the supporting cells.