In a prospective study corneal thickness and specular microscopic findings of corneal endothelium are reported in 37 patients undergoing intracapsular cataract extraction. Central endothelial cell loss was estimated six months after the operation and was found to correlate significantly to the immediate post-operative increase in central corneal thickness. A subgroup of patients showing slight endothelial dystrophy prior to the operation showed a significantly higher increase in corneal thickness fourth day after the operation. Six months after the operation a significant residual increase in corneal thickness was found for this group, while the rest of the patients had returned to near pre-operative levels. No correlation was found between cell loss and residual corneal thickness increase at this time. Six months after the operation a vertical difference in cell density was found. This difference could be correlated to the age of the patient, presumably indicating a less complete redistribution of the cell population in older patients.