Abstract: An eight weeks growth trial was conducted to investigate the effects of dietary melamine inclusion on growth performance, physiological response, renal histopathology and tissue residues in Japanese sea bass (Lateolabrax japonicus).The inclusion levels of melamine in experimental diets were 0, 500, 2000, 5000 and 10000 mg/kg (D1, D2, D3,D4 and D5), respectively. Each diet was fed to triplicate groups of the experimental fish with initial body weight of(30.6?.1) g. Fish were reared in a semi-flow-through system for 56d, and water melamine contents were controlled 0.05); for the whole body composition of Japanese sea bass, no significant difference was discovered in moisture, crude ash or crude protein contents between each treatment (P>0.05); with the increasing supplementation of melamine in the feed, the serum alkaline phosphatase activity (ALP) increased gradually, ALP activity in 5000mg/kg melamine treatment was significant higher than the control group (P0.05); residues of melamine were detected in the liver and muscle of the Japanese sea bass, 57.9 mg of melamine /kg of tissue (wet weight) were detected in the fish liver from daily melamine intake 148.83 mg/kg穡/d groups; 47.63 mg of melamine/kg of tissue and 73.17 mg of melamine/kg of tissue were detected in the fish muscle from daily melamine intake 80.34 mg/kg穡/d and 148.83 mg/kg穡/d groups respectively; histologic examination of kidney revealed that the kidney was harmed by melamine, but no crystal was found in the kidney. The 56d NOAEL (no-observed-adverse-effect-level) for melamine in Japanese sea bass was 8.26 mg/kg穡/d.