Weak concentrations of topical corticosteroids were completely effective in the suppression of graft reactions elicited by full-thickness buttons of pig cornea placed interlamellarly in rabbit corneas. Dexamethasone 0.001% three times a day prevented any graft reactions. The mechanism of this suppression seems to depend mainly on the local anti-inflammatory action of the topical corticosteroids. The experimental model as described appears to be a reliable method of quantitative anti-inflammatory assay of topical solutions.