An assay was developed which identifies monoclonal antibodies recognizing the cell surfaces of sub-populations of chick retinal cells which survive in culture. Antibodies from hybridoma culture supernatants were bound to monolayers of retina cells followed by a fluorescent secondary antibody. The quantitative fluorescence analysis ability of the fluorescence-activated cell sorter (FACS) was used to determine the fluorescence intensity associated with viable single cells and the frequency with which these cells appear in the total population. Hybridomas were generated which define both overlapping and non-overlapping retina cell populations. The cytotoxic activity of many of the monoclonal antibodies was determined on the FACS by propidium iodide exclusion, and the identity of various sub-populations was demonstrated by immunohistochemical staining of retina sections.