This prospective case series study aimed to evaluate the accuracy of computer assisted surgical guide in preserving inferior alveolar nerve during harvesting bone graft determine. The study's variables were included the precision with which CBCT scans identified the position of IAN and their distance away from the autogenous bone graft and the amount of bone available over IAN at external oblique ridge (EOR). The study included six patients with alveolar ridge deficiency that required alveolar ridge augmentation. The surgical guides were proper seated in all patients, except in one patient, in which the guide needed adjustment using stone bur to get well seated and the surgical procedure was completed as usual. The mean harvesting time for all the cases was 17.3 ± 4.1 minutes. The postoperative neurosensory function of the IAN was evaluated based on subjective and objective tests. Using sharp/blunt discrimination test, light touch test and VAS, it was found that all patients (100.0%) had normal sensation from the first week.