Abstract： Objective To study the value of MR diffusion tensor imaging (MR-DTI)using a 3.0 T scanner in anterior ischemic optic neuropathy(AION).Methods A total of 26 patients suffering from unilateral subacute AION were examined using DTI and pattern visual evoked potential(P-VEP).The parameters values of optic nerves including fractional anisotropy (FA),ADC,vertical diffusivity (λ⊥),paralleldiffusion (λ//),P100 value and amplitude were obtained.Paired t-tests were used for comparing the FA,ADC,λ⊥,and λ// values of the two groups.Correlations of DTI parameters and P-VEP parameters were analysed by using the Pearson rank correlation analysis.Results The values of FA,ADC,λ//,and λ_ in the affected nerve were 0.28±0.07,(1.43±0.20) ×103 mm2/s,(1.79±0.16) ×10-3 mm2/s,and (1.25±0.17) ×10-3 mm2/s respectively,and the corresponding values of unaffected nerve were 0.57±0.05,(1.04±0.17) ×10-3 mm2/s,(1.71 ±0.19) × 10-3 mm2/s,and (0.75±0.08) × 10-3 mm2/s respectively.Compared to unaffected contralateral nerves,the mean FA was reduced,the mean ADC,λ⊥ were increased in the affected nerves(t=-19.269,10.537,15.301,P＜0.01).However,there were no significant difference of the λ//(t=l.632,P＞0.05).There was significant negative correlation between ADC and P-VEP amplitude in affected optic nerves (r=-0.722,P＜0.01).There was moderate negative correlation between λ⊥ and P-VEP amplitude in affected optic nerves (r=-0.634,P＜0.01).There was moderate correlation between FA and P-VEP amplitude (r=0.539,P＜0.01).There was no correlation between λ// and P-VEP amplitude.There was moderate negative correlation between FA and P-VEP P100 latency(r =-0.619,P＜0.01).Conclusions DTI can sensitively detect diffusional abnormality of anterior ischemic optic neuropathy.DTI could be used as a supplemental way in the assessment of AION.