Abstract: The purpose of this study is to find the most suitable concentration of feed addition (0, 0.1, 0.3 g/kg rutin) for juvenile GIFT tilapia (Oreochromis niloticus), which was assessed by contents of serum IgM, antiinflammatory cytokines and pro-inflammatory cytokines. Results showed that serum IgM (except for 0.1 g/kg at 45 d), anti-inflammatory cytokine IFN- γ (except for 0.3 g/kg at 45 d) and IL- 10 (at 30 d) significantly increased in rutin addition groups for juvenile GIFT tilapia. With regard to the pro-inflammatory cytokines, TNFα, IL-1β and IL-8 (0.1 g/kg at 30 d and 45 d) significantly decreased in rutin addition groups for juvenile GIFT tilapia. The present study demonstrated that a certain concentration of rutin showed inflammatory response in juvenile GIFT tilapia.