Purpose: To determine the effect of mitomycin-C (MMC) on the cornea after a single intraoperative application. Setting: Department of Ophthalmology, Far Eastern Memorial Hospital, Ban-Chiao, Taipei, Taiwan. Methods: Mechanical epithelium debridement of the central 10.0 mm of the cornea was performed in 63 pigmented rabbits. One group of corneas (MMC1, n = 42) was soaked with MMC 0.01% solution for 2 minutes; the second group (MMC2, n = 42) was soaked with MMC 0.02% solution for 2 minutes. Control corneas (n = 42) were soaked with balanced salt solution for 2 minutes. Changes in the central corneal thickness, clarity, epithelial defect size, endothelial cell density, and endothelial apoptosis in the 3 groups were examined on days 0, 1, 2, 3, 5, 7, and 14. Results: There was a close-dependent increase in corneal thickness, decrease in corneal clarity, and increase in endothelial apoptosis after a single intraoperative application of MMC. The endothelium was significantly swollen and became pleomorphic and polymegethic with a concomitant decrease in endothelial cell density, also in a dose-dependent manner. Conclusions: A single application of MMC on the corneal surface caused dose-dependent corneal edema and endothelial apoptosis in the rabbit model. Further clinical study of human eyes is warranted. (C) 2004 ASCRS and ESCRS.