Inbred rats were actively sensitized with bovine lens protein preparations by various, regimens, care being taken to avoid hyperimmunization. Intravitreal challenge with albuminoid and antigenically corresponding whole and α-crystallin resulted in immunogenic intraocular inflammation. A stronger response was obtained to albuminoid than to α-crystallin used in amounts estimated equal in the in vitro antibody binding. The responses were comparable in these animals when challenged with equal weights of these antigens. In albuminoid-challenged eyes, the inflammation had a slower onset and longer duration with more prominent polymorphonuclear and large mononuclear cell response and more intense cellular exudate into the vitreous than in the case of the soluble antigen. Following single sensitization of rats to crystallin or albuminoid, the immune reaction to whole lens crystallins appeared to be restricted to α-crystallin – anti-α-crystallin antibodies, with no evident involvement of antigenic determinants of other crystallins. These results suggest a dominant role of α-crystallin, either soluble or insoluble at least in the antibody-mediated immunopathological components of the experimental lens-induced uveitis.