To investigate the expression characteristics of sex related gene of FTZ-F1 in the half-smooth tongue-sole ( Cynoglossus semilaevis
), the homologue FTZ-F1 (hsFTZ-F1) full-length cDNA was isolated from the testis by homologous cloning, and the cDNA included the open reading frame and a 66 bp 5'-UTR, along with a 1 619 bp 3'-UTR, encoding a predicted 485 amino acid protein. Sequence, tissue distribution and phylogenic analyses of the FTZ-F1 showed that the hsFTZ-F1 belonged to SF-1/Ad4BP group. The hsFTZ-F1 transcripts were highly abundant in the gonads, kidneys, brain and head-kidneys, but weakly in other tissues. However, the expression level in the brain and head-kidney of female was highly abundant than in the male. The hsFTZ-F1 expression was highly abundant in the embryo than in the larvae, which suggested that the hsFTZ-F1 may be involved in the organogenesis in the tongue sole.