Autoantibodies against corneal epithelium antigens are frequently found in patients with corneal diseases, but also in patients with uveitis. To investigate whether these autoantibodies play a primary role in the pathogenesis of corneal disease we studied the distribution of a 54 kD corneal antigen (isolated in a previous study) within the eye. Animal experiments were performed to determine the accessibility of this antigen by its corresponding antibody. Immunohistochemistry showed that the 54 kD corneal antigen was abundantly present in the rat corneal and conjunctival epithelium. A high concentration of this antigen was seen just above the nuclei in the basal cell layer of the corneal epithelium. The antigen could also be detected in the keratocytes of the corneal stroma, the corneal endothelium and the lens epithelium. The 54 kD corneal antigen was not detected in other parts of the eye, nor could it be found in the rat liver, kidney, spleen, lung or skeletal muscle. Incubation of intact rat eyes with antiserum against the 54 kD corneal antigen in vitro, resulted in a weak binding of immunoglobulins to the corneal surface epithelium cells. Passive transfer experiments, whereby rats received an intravenous injection of antiserum against the 54 kD corneal antigen resulted in a weak deposition of immunoglobulins in the corneal stroma and sclera. However, no antibodies were bound to the corneal epithelium. These observations show that although antibody production to corneal epithelium antigens is easily triggered, these antibodies do not reach the corneal epithelium.