BACKGROUND--This study describes the adhesion systems in the corneal epithelium in the recurrent erosion syndrome and the mechanisms by which binucleate and multinucleate cells are formed within the epithelium. METHODS--Twenty five samples of sliding epithelium were obtained from 23 patients and were examined by conventional light and transmission electron microscopy. RESULTS--The separation of the anchoring system occurred either below the level of the anchoring plaques or at the level of the epithelial cell membrane. Normal and degenerate polymorphonuclear leucocytes were found within and between the epithelial cells and within the anchoring layer. Binucleate and multinucleate cells were found within all the layers of the epithelium as were cysts containing degenerate cellular material. CONCLUSION--The presence of leucocytes and degenerate epithelial cells within the sliding epithelium suggests that these are the source of the metalloproteinases which cleave Bowman's layer below the anchoring system. The formation of binucleate and multinucleate giant cells does not appear to occur by fusion of adjacent cells, but rather by nuclear indentation and cleaving due to an abnormal microtubular system in the cytoskeleton.