The aim of this prospective case series was to evaluate the efficacy and safety of a xenogeneic cortical bone lamina utilized as a "shell" on the buccal aspect of narrow alveolar ridges for horizontal bone augmentation. Fifteen patients requiring multiple implant restorations at sites with moderate to severe horizontal bone deficiency were consecutively enrolled. Horizontal bone augmentation was performed using a xenogeneic cortical bone lamina (XCBL), that was fixed on the buccal aspect of the ridge using titanium screws, and a mixture of particulate autogenous bone graft and porcine hydroxyapatite. Cone-beam computed tomography (CBCT) scans were taken at baseline and 6 months after bone augmentation. The healing was uneventful, with no intra- or post-operative complications. Twenty-seven dental implants were placed in the augmented sites. The calculated average horizontal bone gain from CBCT scans was 4.79 ± 1.64 mm, 5.59 ± 1.51 mm, and 5.79 ± 2.53 mm at 1-, 3- and 5-mm reference points apical to the buccal bone crest, respectively. The present case series demonstrated that the shell technique with the xenogeneic cortical bone lamina and particulate bone graft can be an effective approach for horizontal bone augmentation prior to implant placement.