Left eyed flounders Paralichthys olivaceus, were inoculated with inactivated Vibrio anguillarum vaccine via intramuscular injection to analyze level of cellular immune responses induced by the immunogen.The vaccinated as well as control fish were serially sampled forblood cells 2, 3, 4, 5 weeks post immunization to evaluate phagocytosis activity. Changes of phagocytic index (PI) and phagocytic percentage (PP) determined by measurement of ingesting Staphylococcus aureus were observed with Wright’stain.Results showed that phagocy tosis activity began to increase from 2 weeks post immunization.There isare statistically significant differences in PI and PP(P<0.05) between vaccinated and control fish.The redcell phagocytosis of left-eyed flounders described in the present study for the first time indicates red cellplays an important role not only in respiratory function but also in immune function.