The purpose of the present study was to quantify the optimal zinc requirements of juvenile grouper (Epinephelus malabaricus). Basal diet contained 52 % crude protein from derived egg white and mackerel¡]Scomberomorus commerson¡^muscle. This semipurified basal diet which contained 10.0 mg Zn/kg was supplemented with ZnSO4 at levels of 0, 4, 8, 12, 24, 36 or 140 mg Zn/kg, respectively. The test diets were fed to juvenile groupers with an initial weight of about 5.9 g. All treatments were triplicated, each tank had 12 fish. After 18 weeks of rearing, dietary zinc levels have significant effects on the growth of fish. Weight gain and feed efficiency were significantly lower in grouper fed the unsupplemental diet than the supplemental groups. No significant difference among fish groups was found in survival rate, condition factor, muscle composition, ash contents of vertebra and scale, as well as some hematological parameters. Zinc concentrations in serum, muscle, vertebra and scale were affected by the supplemental zinc level. There was no significant difference in nonspecific immunity parameters including phagocytosis of macrophage, alternative complement pathway (ACH50) activity, agglutination titer and lysozyme activity among dietary treatments. The activity of the copper and zinc metalloenzyme superoxide dismutas in red blood cells was also not affected by dietary zinc intake. Broken-line regression analysis of weight-gain, feed efficiency as well as serum-, vertebra- and scale zinc concentrations against dietary zinc intake indicated requirement values of 33.7, 35.6, 32.5, 28.9 and 32.6 mg Zn/kg diet, respectively. Therefore, based on the results of growth performance and tissue zinc concentrations, the dietary zinc requirement of the juvenile groupers was between 28-36 mg Zn/kg diet.