Temporal lobe epilepsy (TLE) is the most common focal epileptic syndrome in population. Mesial temporal sclerosis (MTS) is a frequent structural abnormality in medically intractable TLE. In this study, we aimed quantitative evaluation of epileptogenic focus using interictal diffusion-weighted magnetic resonance imaging (MRI) method in patients with temporal lobe epilepsy. A total of 72 TLE patients who underwent cranial MRI and 35 control cases were included in this study. 34 hippocampal sclerosis (HS) patients and 38 normal patients were evaluated. Patients were divided into two subgroups as MTS+ and MRI-negative TLE. The measurements of ADC were obtained from the hipocampus head, corpus, tail, amygdala, temporal lobe white matter and cortex bilaterally in the axial ADC map and compared between the groups. In the MTS group, predictive cutoff levels of hippocampal ADCs for identifying pathologic areas were established through receiver operating characteristic (ROC) curve analysis. MTS + group had significantly higher ADC values compared to control group, MTS-negative TLE group and contralateral side (p<0.05). We obtained significantly higher ADCs in right hippocampus corpus and tail, left temporal lobe cortex in MRI-negative TLE group than the contralateral side (p<0.05).