The intracellular survival of a Vibrio anguillarum strain, ingested by head kidney phagocytes and peripheral leukocytes of grouper, Epinephelus awoara, was assessed in vitro by comparing with that of V. parahaemolyticus and Staphylococcus albus. There was an increase in numbers of V. alginolyticus in macrophages from head kidney and peripheral leukocytes during the first 30min after infection, followed by a decline in numbers of viable bacilli between 30 and 180 min after infection while the numbers of V. parahaemolyticus and S. albus which were extremely low keep stable. In addition, cells survival rate infected with V. alginolyticus and V. parahaemolyticus were detected by MTT assay. MTT assays indicated that Cells survival rate of macrophages from head kidney and peripheral leukocytes infected by V. alginolyticus and V.parahaemolyticus decreased in a MOI dependent manner and the values were relatively low, under 65%. These results show that intracellular survival is an important factor determining virulence of bacilli.