Simple bone cyst (SBC), also known as unicameral bone cyst, is a benign, fluid-filled cystic lesion that mainly appears in the long bones of young patients. Simple bone cysts are considered dysplastic or reactive lesions of bone. The most common locations for SBCs are the proximal humerus and femur. Lesions may occasionally be found in the jawbones. Simple bone cysts often have no clinical impact and are usually detected during routine radiographic examinations unless a gross pathologic fracture occurs. When symptoms develop, they may include mild pain, local tenderness and swelling. Computed tomography (CT) scans demonstrate a central, well-defined, mildly expansile or non-expansile, thin-walled lytic lesion, with little or no marginal sclerosis. Magnetic resonance imaging (MRI) usually confirms the cystic nature of the lesion by showing its fluid content. Cystic masses in the hyoid bone are very rare. Here we report an asymptomatic SBC in the hyoid bone, incidentally discovered in a cone-beam computed tomography (CBCT) examination, which appears to be the 2nd reported case.