A novel CC-chemokine gene was isolated from the Japanese flounder Paralichthys olivaceus by expressed sequence tag analysis. The function of this CC-chemokine gene was studied by DNA injection. To investigate the immune responses to the CC-chemokine, a plasmid construct containing the novel CC-chemokine and a CMV promoter was injected into the epaxial muscle of Japanese flounder. Quantification of CC-chemokine protein expressed in serum on 1, 3 and 5 days after plasmid injection were estimated by ELISA. CC-chemokine gene injection increased the migration of phagocytic cells. Macrophage functions such as production of superoxide anion and phagocytosis were also stimulated by this gene injection. Thus, this gene from Japanese flounder has functional similarities to that of a mammalian CC-chemokine gene.