Objective: The collapse of bone is considered to be a normal physiological change following the extraction. This study was performed using pericardium collagen membrane and xenograft for horizontal width augmentation simultaneously with the placement of implant. To evaluate the amount of new bone gain CBCT was used. Subjects and methods: Fifteen patients who met the inclusion criteria were selected from outpatient clinic in the Faculty of Dentistry, Al-Azhar University (boys- Cairo). All the patients showed narrow width in the lower posterior ridge that need to be restored by implant placement. All the cases had guided bone regeneration procedure using xenograft and pericardium membrane. The ridge width was measured preoperatively and 6 months post operatively using (CBCT) to evaluate the amount of bone gain. Results: The ridge width showed a significant increase from 4.51±0.56 pre-operatively to 6.61±0.44 immediately post-operative. This was followed by a decrease to 4.71± 0.6 after 6 months postoperatively. There was no significant difference between values recorded pre-operatively and after 6 months. Conclusion: The results of the current study do not support the use of bovine pericardium membrane with xenografts in horizontal bone augmentation simultaneously with implant placement.