Purpose: The aim of this study was to compare solvent dehydrated human allograft (SDHA; Puros Allograft) and freeze-dried human allograft (FDHA; MinerOss) in order to determine if the allogeneic bone preservation process influences the amount of remaining particles and newly formed bone in maxillary sinus augmentation. Materials and Methods: Subjects requiring maxillary lateral sinus augmentation with ridge height 5 mm were included in this study. Maxillary sinuses were randomly assigned to be grafted with a 1:1 ratio of cortical and cancellous bone, either SDHA or FDHA. In both groups, the graft material was mixed with autogenous bone graft at a ratio of 1:1. Morphologic and histomorphometric analyses were completed 6 months after the grafting procedure. Results: Thirty-four subjects were included in this study. All subjects showed similar demographic characteristics at baseline. Half of the sinuses were grafted with SDHA; the remaining half were grafted with FDHA. Histomorphometric analysis of bone core biopsy samples showed no statistically significant difference between the SDHA or FDHA allogeneic bone substitutes (P = .365), with a mean value of 39.54% ± 0.05% and 31.96% ± 0.08% of mineralized tissue for SDHA and FDHA, respectively. However, a slightly higher mean value of remaining particles was obtained for the FDHA compared with SDHA (18.91% ± 0.09% vs 8.65% ± 0.06%, respectively), although the difference was not statistically significant. Additionally, FDHA demonstrated statistically significantly higher osteoblast, fibroblast, and inflammatory cell numbers. Conclusion: Regardless of the preservation process subtype, allogeneic bone grafting material, in combination with autogenous bone, was demonstrated to be effective for maxillary sinus augmentation bone by means of cellular, vascular, and histomorphometric behavior. Nonetheless, FDHA demonstrated higher cellularity compared to SDHA, suggesting accelerated turnover activity for the latter grafting material. Schlagwörter: alveolar ridge augmentation, bone, dental implant, grafting, maxillary ridge augmentation