The aim of this report is to investigate the efficacy of the sandwich technique for vertical bone augmentation in the atrophic posterior mandible of three patients through clinical and histologic studies. A complete osteotomy was conducted using a piezoelectric device to create segmented bone in the atrophic edentulous area and the segmented bone was elevated 6 mm vertically. Interpositional mineral allograft materials were inserted in the space between the basal bone and the segmented bone. After a mean 5-month healing period, bone biopsies were taken in the grafted areas and implants were placed. Six millimeters of vertical bone gain was achieved in all patients by using the sandwich technique. Histomorphometric analysis of the biopsy specimens showed favorable new bone formation without inflammation.