A 34-year-old man had a posttraumatic maxillary fracture, which was left to take its own course for over 12 years. The only subjective clinical symptom was slight mobility of the anterior maxillary alveolus when the patient ate hard food with the maxillary teeth. The patient was treated by open reduction and fixation with a good functional result. In this case, the fracture line was detected on a preoperative computed tomography scan only after changing the window level and window width. It is important to bear in mind that an undiagnosed old maxillary fracture is not easily identified on radiological examination.