Keratocan is one of the three major keratan sulfate proteoglycans characteristically expressed in cornea. We have isolated cDNA and genomic clones and determined the sequence of the entire human keratocan (Kera) gene. The gene is spread over 7.65 kb of DNA and contains three exons. An open reading frame starting at the beginning of the second exon encodes a protein of 352 aa. The amino acid sequence of keratocan shows high identity among mammalian species. This evolutionary conservation between the keratocan proteins as well as the restricted expression of Kera gene in cornea suggests that this molecule might be important in developing and maintaining corneal transparency.