This case report presents the clinical and histologic evaluation of the application of a cross-linked collagen membrane and a new highly purified bovine xenograft with type 1 collagen fiber preservation (Laddec) in mandibular horizontal ridge augmentation on a 50-year-old woman. Significant bone volume was achieved to restore severe bone defect in order to place two implants. Histomorphometric analysis of a bone core at the augmented site, at 6 months, showed new bone formation with bone substitute particles integrated to new viable bone. Keywords: bovine bone-derived biomaterial, cross-linked collagen membrane, horizontal bone augmentation