Background: This prospective case series aimed to assess the clinical stability of maxillary sinus floors regenerated with mineralized, solvent-dehydrated bone allograft (MSDBA) and restored with dental implants after at least 5 years of function. Materials and Methods: Eleven sinuses in 7 patients (4 bilateral) were augmented with 50% cortical and 50% cancellous MSDBA (Puros, Zimmer Dental Italy srl, Vittorio Veneto, Treviso, Italy). After a mean healing period of 8.1 months, a total of 11 bone specimens (1 per sinus graft) were retrieved and 25 implants were placed. Bone samples were analyzed using histology, histomorphometry, and immunohistochemistry. Standardized periapical radiographs were taken at prosthetic loading (baseline) and annually. Results: There were no complications or failures. Histologically, almost all residual MSDBA particles were surrounded by bone. Histomorphometry characterized the tissue as 39% +/- 1.6% newly formed bone, 34% +/- 1.6% marrow spaces, and 31% +/- 1.4% residual material reflective of high cortical content of the composite graft. Immunohistochemistry indicated that osteoblasts expressed OB-cadherin at high levels. After a mean follow-up of 5.1 years, implants and regenerated bone appeared clinically stable. Radiographically, implants appeared to be surrounded by dense bone and ridges did not lose clinically measurable volume. Conclusions: Composite MSDBA allografts formed good quality maxillary sinus bone without complications after 8.1 months of mean healing time, and demonstrated clinical and radiographic stability after a mean follow-up time of 5.14 years. (Implant Dent 2011; 20: 445-454)