We describe here a method of approaching the maxillary sinus using an osteoperiosteal flap. Like the Caldwell-Luc procedure, the method allows an easy access to the sinus and an adequate visualization. But in addition, it appears to have the advantages of preventing the ingrowth of soft tissue through the osseous defect into the sinus by replacing the bone trap door while promoting healing and retarding infection by preserving the blood supply to the door.