The toxic effects of aflatoxin B1 (AFB1) on Litopanaeus vannamei were examined in terms of growth indices, body composition, hepatopancreas microstructure and biochemical indexes of haemolymph and hepatopancreas. Six isonitrogenous purified diets were fed to shrimp [initial mean weight (0.3±0.02) g] for 8 weeks in triplicate tanks connected to recirculating system. Diets contained different levels of AFB1 (0, 400, 800, 1 200, 1 600, 2 000 μg/kg). Crude protein of whole shrimp had no significant differences (P > 0.05). Body lipid tended to be higher within shrimp fed diets with higher AFB1 level (1 600 and 2 000 μg/kg). The lowest weight gain (304.67%) was found in shrimp fed with 1 200 μg/kg diet. However the shrimp fed with 2 000 μg AFB1/kg got the lowest survival rate (58.33%) and the highest weight gain. Enzyme activities generally indicated a downward trend. Total antioxidant capacity of hepatopancreas decreased significantly (P<0.05) in 2 000 μg/kg diet. The activity of GST, Na+, K+-ATPase and SOD in hepatopancreas reached minimum in shrimp fed with 1 600 μg/kg AFB1 diet, but GST of haemolymph was significantly higher than others (P<0.05). Histological study on shrimp fed more AFB1 exhibited histological changes. Besides, higher AFB1 residues in hepatopancreas were observed in shrimp fed with higher level AFB1. The most AFB1 residues in hepatopancreas were detected at 95.49 μg/kg in shrimp fed with 2 000 μg/kg. However, no AFB1 residue in muscle was detected in all groups.