A number of grafting materials have been used in vertical and horizontal ridge augmentation to enable implant placement in optimal positions. Autogenous block grafts from intraoral or extraoral sites have been used with positive results. Allograft blocks with cortical bone are also used for ridge augmentation. In this case report, a cancellous allograft block was used for horizontal augmentation of the maxilla. The observed increase in ridge width allowed subsequent implant placement after a 5 month healing period. After 4 months the implant was uncovered and restored as a unit in a 4-unit fixed splinted implant reconstruction. The result suggests that cancellous block allografts may be a promising alternative to autogenous block grafts or cortical allograft blocks in treatment of deficient maxillary alveolar ridges to allow subsequent implant placement in optimal position.