Recent studies on reactive oxygen metabolites have suggested that these products may be important mediators in the early tissue damage that develops from immunopathologic inflammations. The superoxide anion appears to be the principal product of the respiratory burst. In order to determine the effects of removing superoxide with superoxide dismutase on modulating the inflammation in experimental phacoanaphylactic endophthalmitis, the animals with this experimental disorder were treated with superoxide dismutase. The treatment resulted in significant reduction of choroidal inflammation, retinal edema and vasculitis, suggesting phlogogenic role of superoxide in the ocular immune-complex disease.