OBJECTIVE To investigate and analyse one hundred-year-old endothelial cells of human transplanted corneal grafts and compare them with intact endothelium of unoperated eyes. METHODS Specular microscopy was performed on seven individuals (14 eyes) aged >100 years and on seven transplanted corneas with endothelial cells of at least 100 years old. All keratoplasties were performed by the same surgeon (PR) 25-35 years before the time of examination. As controls, 14 unoperated healthy individuals (26 eyes) of 90-100 years, 12 individuals (24 eyes) of 48-52 years, 12 students (24 eyes) of 19-24 years and 11 children (22 eyes) from 10 to 14 years of age were photographed and analysed. RESULTS The mean cell density in the oldest age group, over 100 years of age (average 102 years), was very good 2365 cells/mm(2) . The mean cell density in the transplanted corneas, the endothelial cells of which were over 100 years old (mean 106 years), was 923 cells/mm(2) (range 585-1800 cells/mm(2) ). CONCLUSIONS Corneal endothelial cells may remain viable and capable to perform their function over 100 years. Donor corneas up to 70-75 years of age can be approved for transplantation, provided that the endothelial cells have been thoroughly evaluated with vital staining before the operation.