The abundant soluble protein of bovine cornea (CSP) was partially purified by chromatographies on Sephacryl S-200, DEAE cellulose and agarose to which mouse anti-CSP monoclonal antibody produced by the hybridoma technique was conjugated. SDS-polyacrylamide gel electrophoresis of the purified CSP yielded a single band with a molecular weight of 54,000 daltons. Isoelectric focusing of the CSP yielded four bands of pI 6.41, 6.32, 6.22 and 6.16. Chromatofocusing with PBE 94 (Pharmacia Uppsala Sweden) allowed the separation of these four components of CSP with iso-electric points of 6.28, 5.89, 5.85 and 5.68. In order to biochemically differentiate the four components, we attempted ammonium sulfate fractionation and chromatographies on heparin-sepharose and hydroxylapatite. However, these methods failed to separate the four CSP components. We examined whether the CSP was a glycoprotein or not by Western-blotting with various kinds of biotinylated rectins. Con A and UEA-I appeared to slightly bind the CSP. But CSP was not bound in chromatography on Con A-sepharose. These results suggested that the CSP was not a glycoprotein.