The cell coat in human oesophageal biopsies was studied with Alcian Blue, Ruthenium Red, Safranin O, colloidal iron and the ferrocyanide--osmium tetroxide techniques. Alcianophilic material was found on the cell surface of the basal, prickle cell and functional layers, being most abundant on the superficial cells where it appeared as a continuous coat. In the deeper layers, it tended to have a particulate distribution. Some membrane-coating granules were alcianophilic. Ruthenium Red had a particulate distribution over all cell surfaces. Intercellular debris was also stained. Safranin O produced no staining. Colloidal iron stained the cell coat in a particulate manner. The ferrocyanide--osmium technique showed a uniform filamentous cell coat. The oesophageal epithelial cell coats are, in part, acid mucosubstances which, on the surface cells, may have a protective function.