Nerve growth factor (NGF) and its receptor (NGFR) are proteins that have a role in the normal development and survival of neurons in the peripheral and central nervous systems. During development, NGF is necessary for outgrowth of axons and establishment of synapses, and NGFR is the transmembrane protein that binds NGF and brings it into the cell. NGF and NGFR expression in the rat olfactory system have been studied previously, and age differences in NGFR are explored further in this study, using immunocytochemistry and immunoelectron microscopy to determine the changes in two different ages: postnatal day 5 and the adult. Dramatic differences were found in the distribution of NGFR immunoreactivity in the olfactory system of each of the two ages studied. Electron microscopy revealed that glial cells were responsible for this immunoreactivity.