Intranasal sphenoethmoidectomy was originally used primarily for the provision of adequate drainage of acute and subacute bacterial sinusitis. However, the spectrum of inflammatory sinus disease has changed dramatically since the popularization of broad-spectrum antibiotics, and chronic hyperplastic rhinosinusitis has replaced acute sinusitis as the primary indication for ethmoidectomy. In such cases total or almost total disease removal is crucial to providing long-term drainage and ventilation. We describe several modifications of the Yankauer sphenoethmoidectomy technique that enable the sinus surgeon to provide clearance of disease and excellent drainage for all sinuses by complete marsupialization of the sphenoid, ethmoid, and maxillary sinuses. These modifications include (1) complete rather than partial removal of the middle turbinate, (2) extended middle meatal antrostomy with palatine bone resection to the pterygoid process with delineation of the inferior and medial orbital wall, and (3) introduction of operative endoscopes as adjunctive tools in areas inaccessible to conventional visualization. The current technique and results in nearly 2000 procedures are described.