Ectopic eruption of teeth occurs in a variety of locations. Commonly seen in palate and maxillary sinus, they have also been reported in nasal cavity, orbit, mandibular condyle, coronoid process, and facial skin.Here, we report a rare case of recurrent sinusitis caused by ectopic tooth in right ethmoid sinus and successful endoscopic removal of it. The symptoms of the patient disappeared after surgery. Such case has not been yet reported in the English literature.Ectopic tooth is an uncommon cause of sinusitis. It should be considered in patients presenting with recurrent sinusitis unresponsive to medical treatment. Computed tomography of the sinuses is the modality of choice for diagnosis. Endoscopic sinus surgery is the best method for management of such cases.