Rabbits immunized with cell wall antigens of Staphylococcus aureus developed blepharitis after topical challenge with viable S aureus. The lids of these rabbits were thickened and erythematous. Crusting was found around the lashes, and the lids developed loss of lashes and hair. Histopathologic examination of lids from rabbits with blepharitis showed a dense leukocytic infiltrate and dilated blood vessels beneath an intact epidermis and palpebral conjunctival epithelium. The infiltrate contained neutrophils as well as mononuclear cells, including macrophages, plasma cells, and lymphocytes. The meibomian glands appeared normal. Gram's staining of lid sections did not show gram-positive cocci. The results of this study suggest that hypersensitivity to the S aureus cell wall, and particularly the ribitol teichoic acid that it contains, plays a role in the pathogenesis of staphylococcal blepharitis.