A rare case of aneurysmal bone cyst (ABC) located in the mandibular condyle in a 10-year-old boy is presented. The patient came to our attention for a sudden swelling in the right temporomandibular region, the mouth opening was not reduced. A rapid growing mass, depicting soft tissue invasion, in the right condyle of the mandible was found. Clinically and radiographically it resembled to a malignant lesion. The surgical excision of the mandibular condyle allowed a complete removal of the lesion. The histological examination revealed a pseudocystic expanding osteolytic lesion containing blood-filled space separated by connective tissue and many osteoclastic giant cells, which was a conventional vascular ABC. The ABC is an infrequent bone lesion which can only be found very rarely at the craniofacial skeleton. There have been described about 160 cases of ABC originated in the molar region or in upper maxilla and even more rare is the location of this cyst in the mandibular condyle. Only 6 cases were reported in the literature to date. A complete surgical resection of this osteolytic lesion is the treatment of choice considering its high recurrence rate. The condyle was not replaced with any graft. Therefore a functional device was used after surgery to overcome the lack of the condyle and to stimulate the growth of the ramus.