) is one of the most commonly cultured freshwater species in China. However, the development of silver carp aquaculture is threatened by bacterial septicemia. To isolate and study genes disease, we constructed a cDNA library from silver carp liver and kidney tissue using a cfu/mL yielding 2.68×10⁷ cfu recombinants with 97.5terminals to test the completeness of the coding sequence. We successfully sequenced . Among the clones successfully sequenced, 57 sequences were identified to 49 known genes in GenBank. The cDNA library was subsequently screened by PCR yielding a single clone containing the complete coding sequence for MHC class I. The MHC class I was 1 026 bp long and encoded a 341 amino acid (aa) protein that included a leader peptide, 3, and transmembrane and cytosolic domains of 16, 88, 90, 87, and 60 aa, respectively. In addition, we identified sites that were highly conserved among vertebrate MHC class I. Phylogenetic comparison of the complete coding sequences and the α3 domain of MHC class I with other vertebrate species revealed different topology, suggesting a different evolutionary history for different domains of MHC class I and the occurrence of gene recombination among cyprinidae.