Purpose: The aim of this clinical investigation was to evaluate the clinical and radiologic outcomes of a singlestep surgical procedure that includes functional endoscopic sinus surgery (FESS) and maxillary sinus elevation by the lateral window approach in patients with reversible contraindications to sinus elevation. Materials and Methods: Thirty-eight patients with insufficient bone height in the posterior maxilla caused by pneumatization of the sinus and with reversible ear-nose-throat (ENT) contraindications to sinus elevation were recruited for this investigation between January 2010 and January 2012. All patients were treated in a single session under general anesthesia for a total of 69 consecutive sinus augmentations. FESS was performed by an ENT specialist, and an oral surgeon carried out sinus elevation through the lateral window approach. Particulate xenograft was used beneath the sinus membrane. Intraoperative and postoperative complications (eg, membrane tears, rhinosinusitis, graft infection or loss) were reported. Nasal endoscopies were performed at 7, 14, and 30 days and 3 months after treatment. After a healing period of 6 months, 137 implants were inserted. Computed tomography scans were performed after 6 months and 1 year. Results: Intraoperative membrane perforation occurred in only one case. No implant failures were recorded during the follow-up period. Radiologic and clinical findings showed the resolution of ENT disease and good bone graft integration after 1 year. A relapse of mucosal thickening observed in some patients did not influence the graft healing. Conclusion: Preliminary rhinosinusal evaluation by an ENT specialist and computed tomography of the ostiomeatal complex are necessary in patients needing maxillary sinus elevation. A single-step approach to FESS and sinus elevation is a predictable technique to manage patients with ENT reversible contraindications to sinus elevation. Schlagwörter: bone graft, chronic hyperplastic sinusitis, dental implants, functional endoscopic sinus surgery, maxillary sinus elevation, sinus membrane