Extraction of third molar is the most common outpatient surgery of dental treatment. The complication of surgery includes root fracture, dry socket, oroantral communication and nerve injury. Among these complication, lingual nerve injury is very rare and the reason is still obscure. It is generally thought as related to anatomical anomaly or iatrogenic cause. We reported a case of 21-year-old female patient who receive extraction of R't upper and lower third molars. She suffered from post-operative complication of R't tongue anesthesia and was kept followed up until now.