Abstract Nerve growth factor (NGF) and NGF precursor (proNGF)-like material were localized immunohistochemically in diabetic and non-diabetic adult rat retina using affinity-purified immunoglobulins to mature NGF and to synthetic peptides that reproduce sequences of the proNGF. Immunoreactivity for NGF and proNGF was detected in retinal ganglion cells, Müller cells, retinal pigment epithelium and areas adjacent to the internal limiting membrane. Immunolocalization of the NGF receptor using a monoclonal antibody (MC192) revealed positive staining of retinal pigment epithelium and Müller cells but not of ganglion cells. The staining intensity and distribution of NGF, proNGF, and NGF receptor-like immunoreactivity were similar in retinas of diabetic rats. These results suggest that NGF is synthesized endogenously in the retina by both neuronal and non-neuronal cell constituents, and that diabetes has no detectable effect on NGF/NGF receptor distribution and possibly on NGF biosynthesis.