Maxillary sinusitis is one of the most serious complications associated with dental implantation. When local dental treatment with or without antibiotics is not effective, Caldwell-Luc operation is often performed by an oral surgeon. We propose that endoscopic sinus surgery should be employed more widely as the first surgical treatment of choice for odontogenic maxillary sinusitis. This surgery aims to restore ventilation and drainage of paranasal sinuses by correcting the anatomical structures in the nasal cavity and paranasal sinuses intranasally. Unlike Caldwell-Luc procedure, the mucosa in the maxillary sinus is not totally removed; only highly polypous tissue is removed without exposing its bone surface. Resection of infected foci in the alveolar ridge or maxillary floor, when necessary, can be achieved intraorally both during or after endonasal sinus surgery. Postoperative care of irrigating the maxillary sinus with a saline solution at home is usually sufficient to eliminate the inflammation. Aeration of the maxillary sinus is restored without its deformation. Thus, endoscopic sinus surgery is much less invasive and more physiologic, as compared with the classic Caldwell-Luc operation. However, this surgery can be performed safely and securely only by an experienced and trained otolaryngologist. The authors strongly advocate a close collaboration between the dentist or oral surgeon and the otolaryngologist in treating maxillary sinusitis that develops in association with dental illness or treatment such as apical periodontitis, tooth extraction, and implantation. Three illustrative cases are reported.