Objective To explore the effects of ligustrazine (TMP) on acute drug -induced free radical for-mation in guinea pig cochlear ,and to explore possible mechanisms of TMP on gentamycin(GM)-induced ototoxici-ty .Methods Sixty guinea pigs were randomly divided into four groups ,control group ,GM group ,TMP group and TMP+GM group .GM group were injected with GM 120 mg/kg per day .TMP group were injected with TMP 40 mg/kg per day .TMP+GM group were injected with GM and TMP at the same dosage .Control group were injected with normal saline .All groups were injected for consecutive 10 days .Before injection and one day after the last injec-tion ,ABR thresholds were measured .Biochemical assays of Superoxide Dismutase (SOD1 ,SOD2 ,T -SOD) activity and ma1ondia1dehyde(MDA) content in guinea pig cochlear were detected by TBA .Results After the injection , ABR thresholds in GM group were significantly increased compared with those of in control group (P<0 .01) ,with significant difference between GM +TMP and GM group(P<0 .01) .Before and after the experiment ,ABR thresholds in control group were almost unchanged(P>0 .05) .SOD activity was significantly decreased while MDA content was increased in cochlear tissues after GM injection (P<0 .05) .Co -treatment with TMP evidently enhanced SOD activity and decreased MDA content (P<0 .05) .Conclusion TMP may enhance SOD activity and prevent lipid per-oxidation ,thus alleviate GM ototoxicity ,and improve auditory function .