Abstract: This study was conducted to determine the effects of probiotics (Bacillus sp., 109 CFUg-1) on weight gain (WG), amino acids and nutritional composition in the whole body of Litopenaeus vannamei juveniles (initial weight 0.03 g). Survival were not significantly different (P0.05) among all groups. WG of the shrimp fed the control diet was slightly lower than those of shrimp fed diets contained probiotics ranged from 0.5 to 2.0 gkg-1 diet. Specially there was significantly different between the control and the diet containing probiotics 1.0 gkg-1 diet. The percent of moisture, protein and ash in the whole body of shrimp fed diet containing probiotics were not significantly different compared with those of shrimp fed the control diet. However, the content of lipid of shrimp containing probiotics 1.0 and 1.5 gkg-1 diet were higher than that of the control. The content of some amino acids in the whole body could be changed when shrimp fed different probiotics diets.