Nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) staining of striatal neuropil showed inhomogeneities in human fetal and adult brains. Highly reactive patches were seen during fetal and neonatal period, distributed in a lighter stained background matrix. In adult, zones of low NADPH-d reactivity appeared against darker background staining. NADPH-d reactive patches corresponded to and showed a similar shift in the intensity of staining during development as acetylcholinesterase (AChE) reactive striosomes.