Abstract: The topmouth gudgeon (Pseudorasbora parva) was exposed to different concentrations of deltamethrin in statics for 96 h, and the effects of deltamethrin on the specific activities of glutathione S-transferase (GSTs) were evaluated at the end of 6 h, 12 h, 24 h, 36 h, 48 h, 72 h, and 96 h pesticide exposure. The specific activities of GSTs were measured in supernatant after centrifugation (10 000 g) of homogenation from liver, gill, kidney, muscle and ovary of topmouth gudgeon. The results indicated that the specific activities of GSTs were significantly inhibited by deltamethrin in high concentrat ions(0.009 mg/L), and the specific activities of GSTs were reduced 43.7％in liver and 54.3% in gill at the end of 48 h. Under lower concentrations(0.001 mg/L),the specific activities of GSTs in gill were induced, but not significantly. The specific GSTs activities of ovary in tomouth gudgeon, at the end of 96 h exposure to 3.0×10-4 mg/L deltamethrin, were 143% increased compare with that of control. The levels of induction were variable in different organ, and changed with exposed time. Therefore, future studies should be carried out to understand the underlying mechanisms involved in longterm toxicity profile of deltamethrin.