on to culture shrimp with low protein feeds even in intensive systems, which can effectively control water quality under negligible water exchange and sustain healthy culture of shrimp. This study was conducted to evaluate the effects of four dietary protein levels (20%, 25%, 30% and 35%) on selected parameters of immune and antioxidant systems, and growth performance of Litopenaeus vannamei juveniles reared in zero-water exchange biofloc-based intensive culture tanks for a period of 7 weeks. Good water quality was maintained with the promotion and development of biofloc through sucrose addition during the feeding experiment. At the end of the experiment, the total hemocyte count in the hemo- lymph, phagocytic activity of the hemocyte, and antibacterial activity and bacteriolytic activity in the plasma of shrimp showed no significant differences (P N 0.05) among the four treatments with four dietary protein levels. The shrimp in the treatment with 20% dietary protein level had the lowest total