The immunostimulating effect of aloe on respiratory burst activity was investigated by measurements of the chemiluminescent responses (CL) of olive flounder (Paralichthys olivaceus) kidney phagocytes in vitro. The phagocytes incubated with 0.5 and of aloe for 24 hours showed significantly increased respiratory burst activities compared to control. The result of this study suggests that aloe can be used as an immunostimulant for olive flounder culture.