With the use of antisera prepared in rabbits against suspensions of live embryonic chick tissue cells, qualitative differences in cell surface antigens were demonstrated on cells from different embryonic chick tissues by immune agglutination and immunofluorescence. Unabsorbed antisera reacted with both homologous and nonhomologous cells; thorough absorption of the antisera with heterologous tissues removed cross-reacting antibodies, and the antisera acquired a high degree of tissue specificity. Thus, antiretina cell serum absorbed with nonretina cells or tissues, agglutinated only neural retina cells, and was shown by immunofluorescence tests to react specifically with the surface of retina cells, both in cell suspensions and in frozen tissue sections. Comparable results with antisera against cells from embryonic liver and other tissues demonstrated the existence of tissue-specific, phenotypic disparities in the antigenicities of embryonic cell surfaces, in addition to the presence of cell-surface antigens shared by certain classes of cells, and of antigens common to all cells in the embryo. The results are discussed in terms of the possible involvement of such phenotypic determinants in the specification of cell surfaces, in relation to cell recognition and developmental interactions.