Purpose: The aims of this clinical study were to evaluate the occurrence of sinus graft infection and the results of a planned surgical and pharmacologic treatment regimen to eliminate infections and preserve the graft. Materials and Methods: Patients were consecutively treated with sinus floor elevations using the lateral window technique. If a clinical diagnosis of sinus graft infection was made for a patient, a postoperative computed tomographic scan was performed to diagnose involvement of the sinus cavity. Results: Of 198 patients treated with 274 sinus grafts, 8 (2.3%) developed a sinus graft infection. These patients were treated with the same surgical and pharmacologic regimen. Symptoms of infection were recognized, the infected graft was removed, and the remaining graft material was cleansed. The remaining defect was not filled with new graft material; instead, it was left to heal for an extended healing period (average of 10.6 months), and residual bone defects were corrected during implant placement. Acute symptoms of infection disappeared within 48 hours of treatment and all patients healed uneventfully thereafter. All 24 implants placed have survived to date (with implant loading times ranging from 1 to 9 years), resulting in a 100% implant survival rate for these sites with postoperative infection. Conclusions: The overall clinical outcome, including patient satisfaction, achievement of optimal graft volume without subsequent sinus elevation, and long-term implant survival, confirmed the success of this treatment protocol. Schlagwörter: postoperative infection, sinus elevation, sinus graft, sinus graft infection, sinusitis