Abstract: Marbled eel(Anguilla marmorata) is the secondary rotected animal in China. In order to save the genetic information of this rarity and clone the function genes on growth, development and reproduction, a cDNA library was con2 structed by CloneminerTM kit from brain ofmarbled eel.The titer of the amp lified cDNA library was 4.3?06 cfu/mL, the total of recombinantswas 5.16?07 cfu, and the percentage of recombinant efficiencywas about 99.6%, the exogenous inserts of the recombinantswas from 0.43kb to 3.2kb and the average size was 1532 bp.These results showed that cDNA library had excellent quality.Two types of GnRH(mGnRH andcGnRH-II) cDNA sequenceswere isolated from cDNA library by PCR.Sequence analysis showed thatmGnRH cDNA contained an open reading frame(ORF) of 276 bp and encoded 91 amino acid residues,which consisting of a 222amino acid signal pep tide precursor(1-22 amino acid residues),mGnRH decapep tide(23-32 amino acid residues), 32amino acid signal processing site(33-35 amino acid residues), and a 562 amino acid GnRH-associated pep tide(36-91 amino acid residues).cGnRH-II cDNA open reading frame(ORF) contained 264 bases encoded 87 amino acid residues, which consisting of a 242amino acid signal pep tide precursor(1-24 amino acid residues),cGnRH-II decapep tide(25-34 amino acid residues), 32amino acid signal processing site(34-36 amino acid residues), and a 502amino acid GnRH2associated pep tide(37-87 amino acid residues).The homology analysis showed that the percentage ofmGnRH andcGnRH-II precursor sequence identitywith Japanese eel Anguilla japonica is 98%,with fishes of Salmoniformes, Perciformes and Pleuronectiformes is 73%-78%.However, it was relative low with fishes of Cypriniformes(63%-67%).Phylogenetic tree analysis ranked the fish GnRH as three distinct groups,mGnRH and sbGnRH group,cGnRH-II group and sGnRH group, respectively.Expression analysis by RT2PCR showed thatcGnRH-II andmGnRH gene expression had no obvious differences between female and male marbled eel individuals, butmGnRH gene could be expressed in more tissues thancGnRH-II.mGnRH were detected in forebrain,midbrain, hindbrain, pituitary, hypothalamus, liver, heart, sp leen, kidney, intestine, gill, ovary and testis,while expression ofcGnRH-IIwas mainly limited to forebrain,midbrain, hindbrain, ovary and testis.The present work provided evidence of two GnRH inMarbled eel reproductive system and suggested an important role ofmGnRH in reproduction.