Purpose: The aim of this cone beam computed tomography (CBCT) study was to assess bone volume changes in molar sites after modified immediate implant placement with xenografts. Materials and Methods: This prospective study was performed between June 2015 and September 2016. Surgical procedures included modified implant site preparation, atraumatic tooth extraction, implant placement, and bone grafting with deproteinized bovine bone mineral. CBCT scans were taken at the day of surgery and 6 months after surgery. Horizontal and vertical bone dimensional changes were evaluated through these two CBCTs, including variations of horizontal bone thickness (HBT), vertical bone height (VBH), and the distance from the implant platform to the tip of the intradental bone peak (DIP). Results: Fifteen patients with 17 hopeless molars were included, and no implant was lost during the observation period. With measurements at five different parallel levels (0, 1, 2, 4, and 6 mm apical to the implant platform), the mean HBT in millimeters and percentage between these two time points ranged from -0.88 (33%) to -0.03 (0.7%) buccally and -0.45 (12%) to -0.02 (0.4%) lingually. The change of VBH was greater buccally (0.74 ± 0.32 mm, P .01) than lingually (0.40 ± 0.17 mm). DIP was reduced 0.46 ± 0.27 mm mesially and 0.39 ± 0.21 mm distally. Conclusion: In molar sites, flapless modified immediate implant placement with deproteinized bovine bone is a predictable treatment. However, the dimensional change of the ridge should still be expected, and buccal bone resorption is more evident than lingual. Schlagwörter: bone dimensions, cone beam computed tomography, immediate implant placement, molar site