This study evaluated the effects of probiotic and synbiotics of prebiotics and probiotic, on growth performance and non specific immune responses in Nile tilapia. Two prebiotics (fructo oligosaccharide and chitosan) and one probiotic (yeast) were used to formulated the isonitrogenous (30% crude protein) and isocaloric (16.3 KJ/g) diets: one supplemented at 0.1 % with the yeast Saccharomyces cerevisae (YSOO); a second supplemented with a mixture containing 0.1 % of yeast and 1% of fructo oligosaccharide (YSFO); a third supplemented with a mixture containing 0.1 % of yeast and 1% of chitosan (YSCH) and a fourth, a control diet without supplements (CTRL). The diets were fed for 120 days to tilapia fingerling stocked in 9 m-2 net cages at a density of 20 fish per m-2, twice a day at 3% body weight. Results indicate that the fish fed with diets with the probiotic and synbiotics of prebiotics and probiotic supplement (YSOO, YSFO and YSCH) exhibited greater growth and inducing the non specific immune responses (hematocrit, white blood cells and serum lysozyme) than those fed with the control diet (p<0.05). Moreover, a cost of feed was lowest (p<0.05) when YSOO was applied. In conclusion, the diet supplemented with yeast (YSOO) produced the best growth performance and non specific immune responses, suggesting that yeast is an appropriate growth-stimulating additive in tilapia cultivation.