A case of central crystalline dystrophy of Schnyder is presented in which ultrastructural studies were performed on the corneal specimen after penetrating keratoplasty. Electron microscopic changes were documented not only in the anterior but in the posterior stroma and in the corneal endothelium. In the posterior stroma and at the interface between the stroma and Descemet's membrane, numerous ovoid, electron-lucent spaces were present that most likely represented foci of lipid deposition. In addition, rare, focal areas of endothelial cell degeneration were observed that produced minute discontinuities in the endothelial cell covering of Descemet's membrane. Changes in the posterior layers of the cornea in Schnyder's crystalline dystrophy may contribute to the comparatively poorer surgical results obtained with lamellar rather than full-thickness grafts in these cases.