A 240 d growth experiment was conducted in a re-circulated water system to investigate the effects of dietary vitamin A on growth and antioxidant responses of abalone Haliotis discus hannai Ino. Triplicate groups of juvenile abalone [initial mass was (0.96 ± 0.02) g, shell length was (17.70 ± 0.06) mm] were fed to satiation one of three semi-purified diets containing 0, 1×10~3, 1×10~6 IU vitamin A per kilogram diet, respectively. Results showed that the daily increment in shell length (DISL) of abalone in the treatment with 1×10~3 IU vitamin A per kilogram diet was significantly higher than that with 0 or 1×10~6 IU vitamin A per kilogram supplementation (P < 0.05). Vitamin A deficiency (0 IU/kg) significantly elevated the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione reductase (GR) in the viscera of abalone (P < 0.05). In muscle, the effects of vitamin A deficiency on SOD and GPX activities were the same as those in viscera, however, the activity of GR significantly decreased (P < 0.05). Vitamin A deficiency significantly decreased the ratio of CAT to SOD (catalase/superoxide dismutase) in viscera (P < 0.05). Nevertheless, it significantly decreased the ratio of GR to GPX in muscle (P < 0.05). Compared with the supplement of 1×10~3 IU vitamin A per kilogram, excessive vitamin A (1×10~6 IU/kg) had no significant effects on the activities of CAT, SOD and glutathione-S-transferase (GST) (P > 0.05), but significantly elevated GPX and GR activities in viscera (P < 0.05). In muscle, the activities of CAT, SOD, GPX, GST and GR were significantly decreased by the excessive dietary vitamin A supplement (P < 0.05). Compared with the supplement of 1×10~3 IU vitamin A per kilogram, vitamin A-excessive had no significant effect on the value of ratio of CAT to SOD either in viscera or in muscle (P>0.05). The ratio of GR to GPX was significantly decreased in viscera, but significantly elevated in muscle in the vitamin A-excessive group (P < 0.05). In conclusion, optimum supplement of vitamin A (1×10~3 IU/kg) was beneficial for abalone to maintain maximum growth and antioxidant system. Hypo- or hyper-vitaminosis A would decrease growth and the efficiency of scavenging reactive oxygen species (ROS) of abalone. A 240 d growth experiment was conducted in a re-circulated water system to investigate the effects of dietary vitamin A on growth and antioxidant responses of abalone Haliotis discus hannai Ino. Triplicate groups of juvenile abalone [initial mass was (0.96 ± 0.02) g, shell length was (17.70 ± 0.06) mm] were fed to satiation one of three semi-purified diets containing 0, 1 × 10 ~ 3, 1 × 10 ~ 6 IU vitamin A per kilogram diet, respectively. in shell length (DISL) of abalone in the treatment with 1 × 10-3 IU vitamin A per kilogram diet was significantly higher than that with 0 or 1 × 10-6 IU vitamin A per kilogram supplementation (P <0.05). Vitamin A significantly elevated the activities of superoxide dismutase (SOD), glutathione peroxidase (GPX) and glutathione reductase (GR) in the viscera of abalone (P <0.05). In muscle, the effects of vitamin A deficiency on SOD and GPX activities were the same as those in viscera, however, the a (P <0.05). Vitamin A deficiency significantly decreased the ratio of CAT to SOD (catalase / superoxide dismutase) in viscera (P <0.05). P <0.05) Compared with the supplement of 1 × 10-3 IU vitamin A per kilogram, excessive vitamin A (1 × 10 ~ 6 IU / kg) had no significant effects on the activities of CAT, SOD and glutathione-S- The activities of CAT, SOD, GPX, GST and GR were significantly decreased by the excessive dietary vitamin A supplement (P <0.05), but significantly elevated GPX and GR activities in viscera (P <0.05). Compared with the supplement of 1 × 10-3 IU vitamin A per kilogram, vitamin A-excessive had no significant effect on the value of ratio of CAT to SOD either in viscera or muscle (P> 0.05) The ratio of GR to GPX was significantly decreased in viscera, but significantly elevated in muscle in the vitamin A-excessive g roup (P <0.05). In conclusion, optimum supplement of vitamin A (1 × 10 ~ 3 IU / kg) was beneficial for abalone to maintain maximum growth and antioxidant system. Hypo- or hyper-vitaminosis A would decrease growth and the efficiency of scavenging reactive oxygen species (ROS) of abalone.