This study was designed to compare between the use of Khoury's bone shell technique vs titanium-reinforced PTFE membrane for 3D-ridge augmentation of atrophic posterior mandible. Sixteen patients were equally and randomly assigned to either the Khoury or PTFE group. In Khoury group, a mandibular bone block was harvested, split and then fixed to augment the mandibular defect using osteosynthesis screws. In PTFE group, augmentation was achieved using Titanium-reinforced PTFE membranes fixed with bone tacks/screws. A mixture of autogenous and xenogenic graft material at a 1:1 ratio was used in both groups. Vertical and horizontal bone gain were obtained using cone-beam computed tomography (CBCT). Preoperative dimensions were compared with the final dimensions obtained 6 months postoperatively. No significant complications or neurosensory dysfunction were encountered. A solitary patient in the Khoury group experienced limited wound dehiscence, which was treated conservatively. For both groups, there were no significant differences between preoperative and postoperative vertical (p = 0.849 and 0.569) and horizontal (p = 0.778 and 0.367) dimensions. No significant differences exist between the augmentation dimension which can be obtained using either Khoury of Ti-PTFE membranes. Both approaches are delicate and necessitate surgical expertise and experience. Both techniques can be used to achieve predictable augmentation results with a low rate of complications. How to cite this article: Shaker AES, Salem AS, El-Farag SAA, et al. Comparison of Khoury's Bone Shell Technique vs Titanium-reinforced Polytetrafluoroethylene Membrane for 3D-bone Augmentation in Atrophic Posterior Mandible: A Randomized Clinical Trial. J Contemp Dent Pract 2024;25(6):518-526.