Purpose.To examine the effect of donor age on the morphologic variation of cultured human corneal endothelial cells (HCEC).Methods.HCEC were obtained from the remaining corneoscleral rims of seven human corneas used for penetrating keratoplasty. The donor age ranged from 2 to 75 years. Primary cultures were established from explants of the endothelial cell layer, including the Descemet's membrane, and were propagated on culture dishes coated with bovine corneal endothelial extracellular matrix. At the fourth passage, frequency distribution of cell area in the confluent monolayer was calculated and the effect of donor age on cell area was analyzed.Results.The percentage of HCEC with cell area over 2000 &mgr;m2significantly increased with donor age (r= 0.935,p= 0.0007).Conclusion.Cultured HCEC established from older donor tissue display greater heterogeneity. The use of HCEC from younger donors may be preferable to maximize the benefits of HCEC transplantation.