The purpose of this study was to investigate the histomorphometric change in the normal development of human fetal corneal endothelial cells. Eighty one human fetal corneas, ranging from 12 to 40 weeks of gestation, were examined. For determination of gross parameters, corneal diameter and height were measured. Then the corneal endothelium including Descemet's membrane was stained with hematoxylin-eosin using a flat preparation method. In addition to histologic examination under the light microscope, computer-assisted image analysis was performed to determine the cell area, coefficient of variation in cell area and cell density, in both central and peripheral cornea, from each specimen. Total cell count per cornea was obtained by multiplying endothelial cell density by corneal surface area. Linear and nonlinear regression analysis of gestational age and each parameter were used to model corneal endothelial development during the prenatal period. Fetal cornea grows rapidly throughout the prenatal period. During the same period, mean cell area and total cell count also increases gradually, but there is a steep increase in the total cell count in the early period and of the cell area in the late period. The mean cell density decreases rapidly from 16 015 to 6167 cell x mm(-2). There was no significant difference in all parameters except cell density, between the central and peripheral cornea and the difference in cell density was only 2%. In the early prenatal period, there is a rapid increase of total cell count by mitosis, whereas in the late period enlarged endothelial cells cover the rapidly widening inner corneal surface without a significant change in the total cell count.