Abstract: In this study,we report,for the first time,the cloning of the cDNA for pituitary glycoprotein hormoneαsubunit( PGH α) from seahorse,Hippocampus kuda Bleeker,a species of Syngnathiformes. The full length PGHαcDNA was obtained using 5’- and 3’- rapid amplification of cDNA ends(RACE). The full-length cDNAfor the PGHα ofH. kuda was 741bp in size excluding the poly(A) tail,with a 5’UTR of 76bp,a 3’UTR of 314bp,and an open reading frame of 351bp,which encodes a protein of 117 amino acids with a putative signal peptide of 23 amino acid residues and a mature peptide of 94 amino acids. All 10 cysteine residues,2 putative N-linked glycosylation sites,and two proline residues( P41 and P43) are conserved. Sequence analysis revealed that the PGHαmature peptide ofH. kuda shares 50%—61.7% amino acid identity with other vertebrates,and the highest identity(61.7%) with tilapia,a member of Perciformes,and with rice-fieldeel,a member of Synbranchiformes,respectively. The PGHαsignal peptide ofH. kuda shares 8.7%—39.1% amino acid identity with mammalian,avian,amphibian,and other fish. These results indicate that the PGHαof seahorseH. kuda shares relatively low homology with those of other vertebrates, and even other fish examined,suggesting seahorseH. kuda is a special fish and worth further study.