IT is generally agreed that Nasmyth's membrane, which is present on the enamel surface of recently erupted teeth, is composed of an outer cellular and an inner structureless layer, and that shortly after eruption the cells are lost due to degeneration and masticatory trauma. Whether or not the inner structureless layer remains on the surface is a matter of controversy, but it may be inferred from recent papers that it does remain throughout life1–3. This, however, is difficult to envisage in view of the findings of Scott et al. 4 and Scott5, who have demonstrated the wear which takes place continually on the enamel surface of erupted teeth, although it is true that these authors do speak of a ‘cuticle’.