SUMMARYThe interaction of Concanavalin A (Con A) and the surface membranes of the epithelial cells of human oral mucosa, epidermis and guinea‐pig lip was studied. Two methods were used: fluorescent Con A and Con A in combination with horse radish peroxidase. With both methods the surface coat of epithelial cells was stained. The specificity of the staining methods could be demonstrated. The interaction between pemphigus antibodies and the surface membranes of epithelial cells could be blocked by Con