Abstract: This study aimed at determining whether increased body astaxanthin content in Penaeus monodon juvenile resulting from dietary astaxanthin supplementation followed by Vibrio damsela challenge could alter the shrimp's antioxidant defense capability and hepatopancreatic enzymes. Haemolymph total antioxidant status (TAS) and superoxide dismutase (SOD) were chosen as indices of shrimp antioxidant capacity. Hepatopancreatic enzymes measured were aspartate aminotransferase (AST) and alanine aminotransferase (ALT). P. monodon, 5-day old postlarvae, were fed diets supplemented with 0 or 71.5 mg astaxanthin/kg diet for 8 weeks and the resulting juvenile contained 10.5 and 45.6 μg/g body astaxanthin. Shrimp were then subjected to bath challenge of V. damsela. Up to 48 h after challenge, the survival of control shrimp, 36.5±3.2% was significantly lower than that of the astaxanthin-fed (AX) shrimp, 45.2±2.8%. After the bath challenge, AX shrimp had higher TAS and lower SOD and ALT than controls. AST was not influenced by either body astaxanthin or bath challenge. In conclusion, dietary astaxanthin increased body astaxanthin and concomitantly enhanced antioxidant defense capability in P. monodon juveniles, consequently provided protection to some extent against V. damsela challenge in the early stage, which reflected in slightly higher survival and lower ALT.