Purpose: To conduct a histomorphometric investigation comparing the use of enzyme-deantigenic equine bone (EDEB) and anorganic bovine bone (ABB) for maxillary sinus augmentation. Materials and Methods: Forty patients with Cawood Class V atrophic ridges who required maxillary sinus augmentation randomly received EDEB (n = 20) or ABB (n = 20) granules. Six months later, biopsy specimens were obtained, and implants were placed. Bone specimens were subjected to histomorphometric analysis, and newly formed bone (NFB) and residual biomaterial (RB) percentages were calculated. Patients were followed up for 3 years after definitive prosthetic rehabilitation, and implant success and survival rates were determined according to the criteria of Albrektsson and Zarb. Results: All patients healed uneventfully. Histomorphometric results for the EDEB were as follows: NFB = 46.86% ± 12.81% and RB = 11.05% ± 9.27%. For ABB, they were: NFB = 25.12% ± 7.25% and RB = 28.65% ± 9.70%. The difference was significant at a .05 level of confidence both for NFB and RB. At the 3-year follow-up, the implant survival rate was identical in the two groups (100%). Conclusion: Grafting with EDEB resulted in a greater quantity of NFB at implant insertion. No significant clinical differences were observed between the two patient groups at the 3-year follow-up. EDEB was as effective as ABB for sinus augmentation. Keywords: bone remodeling, biomaterial, sinus augmentation, xenograft