The most frequent cause of an oroantral perforation is the extraction of an upper molar. In this article, this for a dental practitioner important entity is discussed in detail. After the etiopathology, clinical and roentgenological diagnosis is discussed. As 6.5% of perforations closes spontaneously, the question is raised wether all perforations should be surgically treated. Those different surgical techniques are then described and emphasis is thereby laid on the difference between a mere perforation and a fistula.