Accidental displacement of an impacted lower third molar into the pterygomandibular space during extraction is a rare complication. The purpose of this article is to report the case of a lower third molar displaced into the pterygomandibular space during an unsuccessful surgical intervention. A 26-year-old male patient presented with infection and trismus was referred to our clinic. The patient's history revealed that he undergone an unsuccessful impacted third molar removal performed by dentist two years ago. The patient was not referred to oral surgeon after the incident, although, the doctor noticed the iatrogenic displacement. On radiological examination, panoramic radiograph and Computed Tomography (CT) scans showed that the displaced tooth was migrated in the pterygomandibular space over the two-year time. Infection and trismus were controlled by antibiotic therapy and physiotherapy before the surgery and the displaced tooth was recovered under local anesthesia. The post-operative period was uneventful and the patient recovered without any sequel.