Purpose: The purpose of this study was to evaluate the three-dimensional radiographic changes of 100% anorganic bovine bone xenograft volume in a grafted maxillary sinus, based on a computerized analysis of cone-beam computed tomography (CBCT) scan. Materials and Methods: A maxillary sinus augmentation procedure done with a lateral approach using 100% anorganic bovine bone was performed in 20 patients. A CBCT scan of the grafted area was taken immediately after the procedure (T1) and 8 to 9 months later (T2). CBCT scan data were analyzed with image processing software to evaluate differences in the volume of grafted material between T1 and T2. Residual ridge height and width were also measured at T1. Results: The mean residual bone height and width at the implant sites was 4.40 ± 0.87 mm and 7.9 ± 2.22 mm, respectively. The mean graft volume was 1,432 ± 539 mm3 and 1,287 ± 498 mm3 at T1 and T2, respectively. A significant difference in graft volume was found between T1 and T2 data by paired t test (P = .01). The mean ratio between the volume at T2 and the volume at T1 was 0.90 ± 0.12, meaning a graft volume contraction of 10%. Conclusion: Within the limits of the present investigation, good stability of anorganic bovine bone graft volume up to 8 months after the grafting procedure was demonstrated. Three-dimensional computed tomographic volumetric assessment seems to be a promising approach to quantify long-term changes in the regenerated area. Keywords: bone graft, maxillary sinus, three-dimensional radiographic changes