Abstract : Determining the difficulty of impacted lower third molar (L3M) is a continuous challenge for oral surgeons. Kim et al., a modification of Pederson scale is one of the indices proposed to estimate the difficulty of (L3M) based on radiographic findings. Preoperative panoramic view were obtained for fifty patients who need (L3M) being extracted the difficulty was predicted according to Kim et al. A clinical evaluation of difficulty was considered according Parant scale (PS) and surgical time (ST). Kin et al. revealed low to accepted sensitivity (23.8%, 58.8%) and low specificity (21.1%, 36.4%). Regarding the likelihood ratios, only the negative likelihood ratios for prediction of Parant categories were significant (3.61) while the other ratios were not. No significant correlation (P= 0.538, 0.229) exist between the index difficulties with PS and ST. Kim index is unreliable to predict extraction difficulty.