Twenty-eight paired human corneas were preserved in minimal essential medium at 31 degrees C and in McCarey-Kaufman medium at 4 degrees C. These grafts were then transplanted in pairs of patients with keratoconus who were age matched as closely as possible. These pairs received donor corneas from the same donor, so for each pair the donor age and time from death to preservation were the same. Visual acuity, central corneal thickness, and endothelial cell counts were compared. During the 1- to 2-year study period, no statistically significant difference in visual acuity, corneal thickness, or endothelial cell density was found between grafts stored in minimal essential medium and those stored in McCarey-Kaufman medium.