Abstract: To study the effect of Vibrio parahaemolyticus challenge on the non-specific immune function of Penaeus monodon,healthy P.monodonaverage body weight(5.65±0.34)gwere used to determine the changes of non-specific immune enzyme activities in hepatopancreas and gill tissues after being injected with sterile 0.86% normal saline and V.parahaemolyticus.Activities of total antioxidant capacity(T-AOC),acid phosphatase(ACP),alkaline phosphatase(ALP)and lysozyme(LSZ)were measured at different sampling time points.The results showed that:compared with the control group,after being challenged with V.parahaemolyticus,T-AOC activities in hepatopancreas and gill were both increased to the peak value at 12 and 6 h(P<0.05),respectively,and then decreased gradually.ACP activities in hepatopancreas were up-regulated significantly at 3 h(P<0.05),then decreased gradually and reached the lowest level at 24 h(P<0.05).In gill,ACP activities were increased to the maximum at 12 h,and then decreased gradually to a lower level than the control at 48 h(P<0.05).ALP activities in hepatopancreas and gill both showed a downward tendency after rising first in general,but did not exhibit the phenomenon of significantly lower than the control group.LSZ activities in hepatopancreas and gill both increased significantly to the peak level at 3 h,and then returned to the control group level gradually.The results indicated that V.parahaemolyticus challenge had noticeable impact on non-specific immune enzyme activities of P.monodon,and significant destructive effect to the shrimp's immune system.