Heterotopic ossification is the formation of the bone outside the skeletal system. This pathologic process may occur in sites such as the skin, subcutaneous tissue, skeletal muscle and fibrous tissue adjacent to joints. A 26-year-old woman came to our clinic with a non-tender, slow-growing left neck mass for two years. CT scan of the neck revealed a 4×2.5 cm, well circumscribed soft tissue mass with irregular high-density component inside. The lesion has no connection with the surrounding bony tissue. The patient received surgical excision. The histopathologic examination revealed heterotopic ossification. No recurrence was noted after follow up for 6 months.