In the course of a detailed study of the anaphylactic theory of sympathetic ophthalmia, a study has been made of the antigenic properties of the uveal tract, especially the uveal pigment, of the eye. From the standpoint of the ophthalmologist the results are of little import beyond their possible correlation with clinical disease. From the standpoint of the immunologist, however, the results appear to be of more scientific interest, in so far as they indicate rather striking immunologic properties for a native body protein. It is, therefore, the purpose of this paper to report the results of this phase of our studies. The anaphylactic theory of sympathetic ophthalmia, advanced and advocated by Elschnig, assumes that sympathetic ophthalmia is an anaphylactic uveitis brought about in the following manner. The injury to the uvea in the exciting eye, by trauma, intraocular tumor, etc., leads to a destruction or disintegration of uveal tissue.