The recurrence of a solitary bone cyst of the mandibular condyle in a costochondral bone graft is reported. A solitary bone cyst of the right condylar head and neck of a 10-year-old boy was treated by total resection and immediate reconstruction with a costochondral bone graft. Two years after the first operation, a recurrence of the solitary bone cyst within the bone graft was noted. An open treatment was performed. A review of the literature on solitary bone cysts and recurrences of solitary bone cysts shows that the case reported is unique. Possible reasons for the recurrence are discussed.