Nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry was used to study the morphology of labeled axonal plexuses in the human lateral temporal cortex. Strongly stained non-pyramidal neurons and a dense NADPH diaphorase-positive network of fibers were observed in all cortical layers. Certain stained fibers are found to give rise to basket-like formations. Notably other fibers seem to innervate small blood vessels. In addition, numerous blood vessels show a punctate labeling over their surfaces. These findings provide new morphological and chemical details of the axonal innervation of the human neocortex.