The full cDNA sequence of hepcidin in grass carp Ctenopharyngodon idellus has been isolated by using RT PCR and RACE method. The hepcidin consists of 774 bp, including an 282 bp open reading frame (ORF), a 117 bp 5′-UTR and a 383 bp 3′-UTR . The 3′-UTR contains a polyadenylation tailed signal (AATAAA) and 1 mRNA instable motifs (ATTTA). The deduced hepcidin protein comprised 93 amino acid residuces with a signal peptide predicded by using SignalP 4.0 program. Putative amino acid sequence of hepcidin shared 27.9%-51.6% identity with its counterparts from other fish species. Phylogenetic tree constructed by using neighbor joining method revealed that prohepcidin was clustered with that from other teleost fish reported previously. The transcription of hepcidin was examined by quantitative real time PCR, and its mRNA was mainly expressed in liver, spleen and head kidney, and increased significantly in liver, spleen and head kidney between 4 h and 48 h after injection with Flavobacterium columnare.