This article was designed to report the clinical observation of acute left-hand side sinusitis and oroanthral fistula that developed in a patient after she had undergone the operation of sinus-lifting and dental implantation. The authors emphasize the inter-disciplinary character of this problem and the necessity to include counseling by an otorhinolaryngologist and computed tomography investigation of the nasal cavity and paranasal sinuses in the protocol of the postoperative examination.