A feeding study was conducted to investigate the effect of dietary supplementation of zeolite (silicate clay) on growth performance, digestive enzymes, immunity and gut bacteria count of Nile tilapia, Oreochromis niloticus (L.) fingerlings. Three isonitrogenous (300 g/kg crude protein) and isocaloric (19.45 MJ/kg gross energy) diets were formulated. Each diet was supplemented with zeolite at levels; 0 (control), 5 and 10g/kg diet.  After 84 days of feeding trial, the highest weight gain, specific growth rate, protein efficiency ratio and the best feed conversion ratio were recorded in fish fed either 5 or 10 g/kg diet zeolite. The addition of zeolite improved significantly hematocrit, hemoglobin, red blood cells count, and white blood cells compared with control diet. In addition, the lowest activities of serum alanine and aspartate aminotransferase and alkaline phosphatase were observed in fish fed diets supplemented with 10 g/kg diet zeolite. No significant differences were found in chemical composition of fish fed treatment diets. Results of this study indicated that the addition of zeolite as feed additive enhanced the growth, feed utilization and hematology and blood biochemistry of Nile tilapia.