In this article, a novel endoscopic technique used to close oro-antral fistulas will be described. In the technique described here, 24 cases were surgically treated between May 2011, and November 2014. Under endonasal endoscopic examination following partial inferior uncinectomy, the natural ostium of the maxillary sinus was identified; through this tract, a curved aspirator was advanced into the sinus. If present, we extracted endoscopically tissues causing obliteration of the ostium through the Caldwell-Luc antrostomy, taking care to preserve the integrity of the natural ostium. In the technique described here, endoscopic examination using the Caldwell-Luc approach, the inside of the maxillary sinus is explored fully, existing infection and polyps are eliminated locally, and natural patency of the maxillary sinus ostium can be achieved. The graft used to obliterate the oroantral fistula can be easily harvested from the bone of the anterior wall of the maxillary sinus by accessing the surgical entry tract.