Inverted papilloma is generally considered a benign unilateral sinonasal tumor. Its synchronous bilateral multicentric occurrence is extremely rare. A 22-year-old male patient presented with stage III inverted papilloma involving both ethmoid sinuses, both frontal sinuses, and cribriform area. The patient also had a large osteoma emanating from the basal part of the frontal sinus septum, which completely obstructed both nasofrontal recesses, leaving no communication between the sinuses and the nasal cavity. The frontal sinus septum was intact, so there was no communication between the 2 sides either. Following the era of aggressive surgical approaches dominated by lateral rhinotomy and medial maxillectomy, the advent of endoscopic techniques has dramatically improved visualization of sinus chambers and nasal cavity, resulting in lower morbidity and similar results to those achieved with open surgical procedures. In our patient, the concomitant presence of a huge frontal sinus osteoma posed an unacceptable risk for endoscopic resection due to the possible residual disease in the nasofrontal recess regions. Surgical resection remains the mainstay treatment and should be tailored in accordance with the localization and spread of disease. The surgeon should be ready to use different surgical approaches and, if intraoperatively needed, to modify them accordingly.