Traumatic (simple) bone cyst (TBC) is an empty nonepithelial-lined cavity of the jaws. The majority of TBCs are located in the body or symphysis of the mandible. Clinically, the lesion is asymptomatic and often discovered incidentally on routine radiographic examination as a noncorticated sharply defined radiolucent area with undulating borders. Because tissues for histologic examination may be scant or nonexistent, the definite diagnosis is invariably achieved during surgery when the lesion is empty. In this report, we present a case of unusual bilateral synchronous TBCs of the mandible with possible traumatic etiology, featuring significant buccolingual expansion of the mandibular ramus and body, presence of septa, and probable displacement of the inferior alveolar canal.