Two types of complementary DNAs (cDNA) encoding the precursor of salmon gonadotropin-releasing hormone (sGnRH, [Trp7, Leu8] GnRH) are cloned and sequenced from common carp brain using rapid amplification of cDNA ends (RACE). The two cDNAs are referred to sGnRH cDNA1 and cDNA2, and the full-length fragment of cDNA1 and cDNA2 were 393 and 478 bp, respectively. Two sGnRH cDNAs contain an open reading frame of 285 bp, which encodes the sGnRH precursor including 94 amino acid residues. The sGnRH precursors consist of a signal peptide, sGnRH decapeptide and a GnRH-associated peptide (GAP) which is linked by the processing site (Gly-Lys-Arg). Two different sGnRH genes are characterized by intron trapping, and they share a similar structure composed of four exons and three introns. The nucleotide sequences identity of intron 1, intron 2 and intron 3 in sGnRH gene1 and gene2 are 71.1, 76. 1 and 88.0%, respectively. The basic structure and encoding architecture of sGnRH cDNAs and genes are similar with the reported GnRH. It is presumed that all the GnRH variants may evolve from a common ancestral molecular. Southern blot results confirm further the conclusion that there are two differential sGnRH genes in common carp genome. The results of reverse transcription-polymerase chain reaction (RT-PCR) assaying show that the two sGnRH genes co-express in the dissected brain regions, pituitary and ovary with the exception of expression of sGnRH genes in testis. According to the co-existence of two sGnRH genes in distinct brain regions,pituitary and ovary, it is presumed that sGnRH plays an important role in the regulation of hypothalamic-pituitary-gonadal (HPG) axis,and that sGnRH also operates as the neuromodulator, autocrine and/or paracrine regulator.