The nutritional effects of dietary taurine on the growth, body composition and tissue free amino acid concentrations in Nile tilapia were evaluated.Three hundred tilapias[initial body weight(5.89±0.03)g]were randomly divided into five groups with three replicate tanks at a stock density of twenty fish in each replicate.Five diets were formulated to contain 0, 0.4%, 0.8%, 1.2%, and 1.6% taurine and were allocated to each of the groups of fish twice a day for a feeding period of 56 days.The fish fed the diet at 0.8% taurine got highest weight gain(P<0.05).Dietary taurine levels at 0.4%-1.6% increased feed intake, hepatosomatic index and viscera index, but reduced feed conversion ratio(P<0.05);Both whole-body moisture and ash contents decreased but whole-body crude protein and lipid contents increased with the increase of dietary taurine level(P<0.05);Quadratic curve analysis indicated that the optimal level of dietary taurine for tilapia growth was 0.75% based on weight gain.Taurine concentrations in serum, liver, muscle and whole-body fish were positively linearly correlated with the dietary taurine levels, and the values for these tissues in taurine-treated groups were significantly higher than those of control group(P<0.05).With the increase of dietary taurine, free amino acid concentrations in liver and muscle gradually decreased, and the values in taurine-treated groups were significantly lower than those in control group(P<0.05).