Starry flounder, which are recently increasingly cultured in Korea, are known to highly vulnerable to Streptococcus parauberis infection. Five groups of starry flounder (n=30 for each group) were vaccinated with S. parauberis formalin-killed whole cells by intraperitoneal injection at a final concentration of 0, 0.01, 0.1, 1 and 10 mg fish-1. Specific antibody production of 1 and 10 mg fish-1 administered groups significantly increased at four weeks post immunization. All vaccinated groups showed higher survival rates than a control group when five groups of fish were challenged with S. parauberis at a dose of 1.14×104 cfu fish-1 and 1.14×102 cfu fish-1, respectively. In articular, 0.1 or higher concentrations of formalin killed bacterial cells are able to confer the fish high protection against S.parauberis infection.