The ability of the cornea to maintain its transparency after surgery depends primarily upon the integrity of the corneal endothelium and in corneal grafting this is important for both donor and recipient eyes. The corneal endothelium may be significantly affected in various conditions of the anterior segment, especially if these exist over a considerable period of time. These conditions include superficial keratopathy, long-term contact lens wear, cornea guttata and low-grade anterior uveitis, especially chronic cyclitis which may be almost imperceptible clinically. The suitability of such corneas for use as donor material as well as the response of the eyes to anterior segment surgery can be assessed by specular microscopy and this may become even more important in the future as long-term contact lens wearers become more numerous in the community.