Specular microscopy allows a direct evaluation of the corneal endothelium in intact donor eyes. It is therefore superior to previous methods for assessing donor material for penetrating keratoplasties. In a study of 278 eyes (139 donors) 226 could be examined by specular microscopy without any preparatory major manipulations. Twenty-four pairs and 12 single eyes (27%) of the 226 corneas were considered not suitable for grafts according to their morphologic endothelial changes. The discarded eyes were found all normal at conventional slit-lamp examination. Specular microscopy of the endothelium was not possible in 52 eyes as the corneal swelling was already too advanced.