To investigate the therapeutic potential of mitomycin C (MMC) in the management of proliferative vitreoretinopathy (PVR), antiproliferative effect of MMC on rabbit retinal pigment epithelial (RPE) cells, its intraocular toxicity, and its preventive effect on experimental PVR were investigated. Cultured rabbit RPE cells were exposed to various concentrations of MMC ranging from 1.0 × 10^-3 to 1.0 µg/ml for 72 hours. The RPE cells were then cultured in a medium without MMC for another 7 days, and the cells were harvested and counted. Toxicity of MMC to rabbit retina was evaluated after intravitreal injection of MMC by means of clinical observation, electrophysiologic test, and histopathologic examination. To test antiproliferative effect of MMC on experimental PVR, 200,000 cultured RPE cells were injected into the vitreous cavity of pigmented rabbits, and either 0.2 µg or 1.0 µg MMC was injected intravitreally 24 hours after RPE cell injection. Two to four weeks later, the vitreoretinal status was compared between MMC-treated eyes and control eyes. The antiproliferative effect of MMC on RPE cells was evident at the concentration of 1.0 × 10^-2 µg/ml. The drug concentration required for 50% inhibition of growth was 3 × 10^-2 µg/ml. Nontoxic intraocular doses of MMC were 2.0 µg in rabbit eyes with normal vitreous and 1.0 µg in rabbit eyes with gas-compressed vitreous. The rates of traction retinal detachment after intravitreal RPE cell injection were reduced in the eyes treated with MMC compared with control eyes. These results indicate that MMC may have clinical application to the treatment of PVR.