The Dmrt family of genes are involved in sex differentiation in different species of invertebrates,and some vertebrates including human.In this study,we cloned the full-length cDNA of ayu(Plecoglossus altivelis)Dmrt1 and DmrtA2.Sequence and phylogenetic tree analyses showed ayu Dmrt1 showed highest similarity to that of Oncorhynchus mykiss while ayu DmrtA2 is most similar to that of Oryzias latipes.Fluorescence-based quantitative reverse transcription PCR(qRT-PCR)revealed the Dmrt1 was predominantly expressed in the testis.At the larval stages,Dmrt1 mRNA expression level was highest during 52–64 days post hatching(dph)and at the gastrula stage during embryonic development.DmrtA2,meanwhile,was specifically expressed in the ovary and was highly expressed in the female brain tissue,but not male brain tissue.During the larval stages,DmrtA2 expression remained high before day 34,and then fluctuated while generally decreasing.During embryonic development,DmrtA2 expression increased gradually and peaked at the hatching stage.Our data suggest that ayu Dmrt1 might participate in the differentiation and maintenance of testis while DmrtA2 may play a role in ovary-differentiation and mature-ovary maintenance.DmrtA2 might also participate in brain development. The Dmrt family of genes are involved in sex differentiation in different species of invertebrates, and some vertebrates for human. This study, we cloned the full-length cDNA of ayu (Plecoglossus altivelis) Dmrt1 and DmrtA2.Sequence and phylogenetic tree analyzes showed ayu Dmrt1 showed highest similarity to that of Oncorhynchus mykiss while ayu DmrtA2 was the most similar to that of Oryzias latipes.Fluorescence-based quantitative reverse transcription PCR (qRT-PCR) revealed the Dmrt1 was predominantly expressed in the testis. At the larval stages, Dmrt1 mRNA expression level was highest during 52-64 days post hatching (dph) and at the gastrula stage during embryonic development. DmrtA2, meanwhile, was specifically expressed in the ovary and was highly expressed in the female brain tissue, but not male brain tissue. the larval stages, DmrtA2 expression remained high before day 34, and then fluctuated while generally decreasing. During embryonic development, DmrtA2 expression increased gradual ly and peaked at the hatching stage. Our data suggest that ayu Dmrt1 might participate in the differentiation and maintenance of testis while DmrtA2 may play a role in ovary-differentiation and mature-ovary maintenance. DmrtA2 might participate in brain development.