The reactions of lectins with dissociated and cultured epithelial cells from hyperplastic lenses of two unrelated chick strains, Hy-1 and Hy-2, characterised by hyperplasia of the lens epithelium, and lenses of a normal genotype (N) were investigated using four different lectins. Three methods of monitoring lectin-binding to cell surfaces were employed. Each of the four lectins used showed an individual pattern of reactivity to separated membrane components. Data obtained with the three labelling methods showed the same trend viz: increased agglutinability and high affinity for binding of all four lectins by Hy-1 and Hy-2 cells. These results suggest that Hy-1 and Hy-2 lens epithelial cells are characterised by alteration in their cell surfaces.