A case report involving vertical root fracture in an endodontically treated mandibular left first molar is presented. Pain and extensive tissue damage occurred in the area 2 years after root canal therapy. The periapical radiograph suggested endodontic failure, and re-treatment was initially considered. However, the problem was related to a complete vertical root fracture in the distal root, which was only visible after removal of the gold crown. The toorth was extracted because severe periodontal destruction had been caused by the root fracture.