Abstract [Objective] This study aimed to obtain IL-IO （interleukin 10） full-length cD- NA of common carp （Cyprinus carpio L.） and conduct the sequence analysis. []~lethod] The differentially expressed cDNA fragment was obtained by DD-RTPCR （differential display RT-PCR）. The cDNA library of peripheral blood leukocytes which were separated from common carp and stimulated by mitogen was screened with a probe labeled with DIG （digoxigenin）. The IL-IO full-length cDNA was cloned from 0.8x104 pfu of recombinant phages, and the sequence analysis and homology com- parison were carried out. [Result] Sequence analysis indicated that the IL-IO full- length cDNA of common carp was 1 117 bp long, containing a.55 bp 5＇-UTR, a 522 bp 3＂-UTR, and a 540 bp open reading frame（ORF） encoding 179 amino acids. In addition, there were three mRNA instability motifs （ATTTA） in the 3＂-untranslated region. The deduced protein sequence shared typical sequence features of the IL-IO family. Homology comparison indicated that the obtained sequence shared 89.1% homology with the carp IL-IO gene from GenBank. [Conclusion] This study laid foun- dation for further study of the expression manner, functional characteristic and regu- lation mechanism of IL-IO in vivo and the interaction mechanism in the inflammatory reaction and immune response.