Studies of the central nervous system have localized the zinc-transporter-3 (ZnT-3) protein to synaptic vesicles containing glutamate and zinc. We have examined the distribution of the ZnT-3 protein in the light-adapted mouse retina using immunohistochemical techniques. Light microscopic analysis of 15-30-microm retinal sections revealed a rich band of ZnT-3 protein in the region of the outer limiting membrane and photoreceptor inner segments. ZnT-3 reactivity was also present in the outer plexiform, inner nuclear, inner plexiform, and ganglion cell layers. The outer nuclear layer and photoreceptor outer segments did not exhibit ZnT-3 immunoreactivity. In the light-adapted murine retina, ZnT-3 appears localized in regions which have been found reactive for ionic zinc.