A case of removal of a fractured root displaced into the maxillary sinus by CaldwellLuc procedure with the rigid nasopharyngoscope is presented in this report. A 45-year old Thai woman was referred from a local hospital to the dental department of Chiangrai hospital because a root of the maxillary right first molar was fractured and displaced into the maxillary sinus while being removed 3 hours previously. The patient displayed the clinical feature of a remaining empty socket of the maxillary right first molar. The radiographic examination showed the fractured root in the maxillary sinus. The final diagnosis was the fractured root fragment of maxillary right first molar displaced into maxillary sinus with oroantral fistula. The patient was treated by Caldwell-Luc procedure with the rigid nasopharyngoscope to remove the fractured root fragment quickly. The ulceration healed well and the maxillary sinus was normal with no infection. In addition, the causes of root fracture while being extraction and the fractured root was displaced to adjacent structures were reviewed in order to prevent complications.