Staphylococcus aureus is an important cause of infectious disease of the eye and hypersensitivity lesions of the cornea including phlyctenules and catarrhal infiltrates. Because little is known about ocular immunity to S. aureus, we measured antibody levels to ribitol teichoic acid, the major antigenic determinant of S. aureus, in rabbit serum and tears using an enzyme-linked immunosorbent assay after immunization with S. aureus antigens using the following routes: intradermal injection of cell wall mixed with complete Freund's adjuvant, subconjunctival injection of cell wall mixed with complete Freund's adjuvant, topical application of cell wall to the eye, and topical application of viable S. aureus to the eye. All four immunization groups showed an IgG antibody response to ribitol teichoic acid in serum and tears with the highest titers in serum found after intradermal immunization with cell wall and the highest titers in tears found after topical application of S. aureus. All four immunization routes showed an IgA antibody response to ribitol teichoic acid in tears with the highest titers found after subconjunctival immunization with cell wall. There was no IgA response to ribitol teichoic acid in serum in any group. The results of this study suggest that ocular immune responses to S. aureus may be influenced by exposure to staphylococcal antigens not only in the external eye but also at sites remote from the eye.