Purpose: To present a rare clinical case of migration of a displaced implant fragment from the maxillary sinus to the stomach. Materials and methods: A 66-year-old man was referred from a local dental clinic to remove a displaced implant apical fragment in the left maxillary sinus. After 15 days from the displacement, no foreign body was seen in the maxillary sinus or in any other craniofacial cavity. Thoracic and abdominal radiographs were taken, and a 3 × 3 mm radiopaque object, which corresponded to the piece of implant fragment, was detected within the patient's stomach. Results: Follow-up radiographs were taken to monitor the progress after 1 week, and it was found that the radiopaque object had disappeared. Conclusions: A displaced dental implant fragment in the maxillary sinus can migrate and exit from the maxillary sinus within a few days. Since it presents a potential risk for swallowing or aspiration, displaced implants or other objects in the maxillary sinus should be removed immediately. Before removal, additional radiographs are recommended to confirm the current position of the implant. Keywords: complication, dental implant, displacement, maxillary sinus, migration The authors state that there are no conflicts of interest in connection with this article.