A significant linear correlation was found between increase in corneal thickness (delta CT) in the immediate postoperative period and percentage of cell loss one and six months after surgery in a prospective study on cataract surgery. Eyes were grouped according to delta CT, and the groups were compared according to the percentage of cell loss. Eyes with delta CT of 0.1 mm or more at five days lost significantly more cells at one and six months than eyes with delta CT of less than 0.025 mm. Eyes were then regrouped according to the percentage of cell loss. Those with cell loss of 30% or more were found to have significantly greater delta CT at 48 hours and five days than eyes with cell loss of less than 30%. The derived probability of cell loss of 30% or more increases the greater the value of delta CT. For delta CT of 100 micron or more at five days, the probability of high cell loss is 30%; this is nearly three times the likelihood that high cell loss had occurred when delta CT is less than 100 micron. Our results suggest that delta CT could be a useful clinical indicator of endothelial cell loss.