A novel gene, which was a homologue of Arabidopsis COI1 was isolated from rice (Oryza sativa L.) by RT-PCR and designated as OsCOI1. It encoded a protein of 595 amino acids. The similar F-box motif and 16 leucine-rich repeats were found in the deduced protein OsCOI1. OsCOI1 and COI1 showed high homology (74%) at amino acid level. Semi-quantitative RT-PCR and Northern blot analysis demonstrated that the expression of OsCOI1 in rice varied obviously after treatment with MeJA and ABA but was not affected by SA and ET, suggesting that the specific function of OsCOI1 in JA signal pathway and related ABA pathway.