Seventy-six patients with oroantral communications after tooth extraction and chronic maxillary sinusitis were treated as follows: bacterial cultures were taken in all of them and maxillary sinuses were irrigated with an antibiotic from the cephalosporin group. Then, in 36 patients, drainage using the Caldwell-Luc procedure was performed, including a naso-antral window. In all patients operations were completed by closing oroantral communications with flaps of the mucosa of the alveolar process close to the fistula. Antibiotics according to antibiogram were administered to all patients at least 10 days after surgery. Retrospective comparison between the results obtained in the first group and those in the second group 1, 3 and 6 months after operation was based on objective findings (condition of the oroantral communication, maxillary sinusitis), side effects (pain, numbness of the operated area, headache) and control radiographs (clear maxillary sinus or with mucosal thickening). The study suggests that transnasal drainage is not required in maxillary sinus surgery and in the closure of oroantral communications. Equally good results are achieved by treating with antibiotics and without drainage of the maxillary sinus into the nose.