We evaluated the effect of low doses of mitomycin C (MMC) in subconjunctival injection on fibroblast viability. Eighteen rabbits received subconjunctival injections: group 1 was injected with balanced salt solution (BSS), group 2 received MMC 0.025 mg, and group 3 MMC 0.005 mg. Tissue samples were taken 1 h after the injection (conjunctiva, sclera and cornea at 0 and 90 degrees) and cultured. The average scleral and conjunctival outgrowth in the MMC-treated groups was significantly inferior to the outgrowth of the samples treated with BSS. Subconjunctival injections of MMC (0. 025 and 0.005 mg) have an inhibitory effect on conjunctiva at 0 degrees and on scleral fibroblast populations.