We investigated the mechanism for amplification of intraocular inflammation in rats with experimental autoimmune uveitis by examining the chemotaxis potentials of peroxidized lipids extracted from the retinas. Utilizing thin layer chromatography, we found that the peroxidized products isolated from the inflamed retinas were fatty acid hydroperoxides that corresponded to the autooxidized products from commercial methyl docosahexaenoate, with Rf values ranging from 0.30 to 0.37. These were not demonstrated in similar preparations from normal retinas or in unoxidized docosahexaenoate. Boyden chamber assay revealed that the hydroperoxides isolated from inflamed eyes and the products of oxidized methyl docosahexaenoate possessed significantly higher chemotactic activity than did the retinal lipids isolated from normal eyes (P less than 0.01). These findings may help to explain the mechanism of inflammatory amplification induced by peroxidized retinal lipids that is seen in this animal model of uveitis.