The distribution of the Ca2+ binding protein parvalbumin was studied in the rat retina with immunocytochemistry using a mouse monoclonal antibody. Specific parvalbumin immunoreactivity was identified within a subpopulation of ganglion cells and a subpopulation of amacrine cells. The topographical data provided by the present study may serve as a basis for a functional characterization of parvalbumin's role in the nervous system.