A major glycoprotein of relative molecular weight of 130,000 daltons of chick lens cell membranes was identified by Concanavalin-A staining and enriched for by Con A-Sepharose chromatography. Using both Con A binding and immunological analyses with a specific polyclonal antibody, the glycoprotein was detected in chick lens epithelium, annular pad, cortex and nucleus. Localization to the plasma membranes of lens cells was demonstrated by immunofluorescence. A similar protein, which cross-reacts with the antibody to the chick protein and also binds Con A was demonstrated in human and bovine lenses.