Oroantral communication is an open connection between the oral cavity and maxillary sinus. It most often occurs after the extraction of upper distal teeth, especially molars. In addition to tooth extraction, it can be complication of implant therapy and cyst enucleation. Other possible aetiologies are trauma and pathological events such as osteomyelitis. Not treated oroantral communication can lead to epithelialization and subsequent oroantral fistula creation. Oroantral fistula is a pathological epithelialized communication between the oral cavity and the maxillary sinus. Constant communication between the oral cavity and the sinus enables migration of oral microflora into the maxillary sinus and causes inflammation. During the treatment of oroantral fistula, it is necessary to pay attention to possible sinus inflammation, which have to be attended before surgical closure of the fistula. Surgical procedure should be chosen individually according to the needs and medical condition of the patient. The possible complications depend on the type of procedure performed. Some of the more common ones are reduced vestibular depth, edema, flap necrosis and wound dehiscence. Occurrence of complications can be influenced by the inexperience of the doctor and improper selection of the procedure. However, for the outcome of the therapy, apart from the competence of the doctor, patients' proper adherence to postoperative instructions is important.