Purpose: The aim of this study was to assess bone ingrowth into porous titanium granules used for maxillary sinus augmentation. Materials and Methods: Eighteen biopsy specimens from 17 patients participating in a clinical trial on sinus augmentation using porous titanium granules (PTG) were received in the laboratory. The specimens (trephine cores of 4.5 mm) were obtained 6 months after PTG placement. After being embedded in methacrylate, the samples were scanned in a microcomputed tomography (micro-CT) scanner. Specimens were then cut along the long axis and central slices were ground to 70 µm before staining with hematoxylin and eosin. Results: The micro-CT analysis demonstrated an average bone fill of 19% (standard deviation [SD] 5.8%), whereas the graft material occupied 22.7% (SD 4.7%). The volume of newly formed bone decreased with the distance from the residual bone of the sinus floor. Two-dimensional histomorphometric analysis demonstrated a mean area of new bone of 16.1% (SD 9.4%). The PTG alone occupied 25.9% of the total mean area (SD 6.1%). The newly formed bone consisted mainly of woven bone growing in close contact with the granules and bridging the intergranular space. The remaining area was occupied predominantly by nonmineralized connective tissue. There were no signs of inflammation in any of the biopsy specimens. Conclusions: After 6 months, new bone had formed at a similar rate and quality as has been reported for other well-recognized bone graft substitutes. The new bone formed in close contact with the PTG, suggesting that the material is osteoconductive.