Oxidized and reduced proteins were prepared from the ocular lenses of sheep, swine, chicken and fish (pike). The proteins were prepared under conditions designed to avoid denaturation and to produce relatively pure compounds. Serologic studies revealed that species specificity is demonstrable in the proteins from chicken and fish lenses, but in the more closely related species (swine and sheep) this characteristic is not so evident. Serologic differences may be detected in the lens preparations from a single species, depending on the redox state of the protein.