Purpose: To report an unusual case of dermoid cyst of the frontal boneCase report: We report a case of 28-year-old man with a history of painless progressive proptosis of the left eye. CT-Scan was showed a hypodense lesion that mainly located within the frontal bone with only a small intraorbital involvement. Excisional biopsy was performed and histopathologic examination was compatible with dermoid cyst. Dermoid cysts are the most common orbital cystic lesions in childhood which commonly present as a painless palpable mass in the superotemporal aspect of the orbit. Typically, orbital dermoids involved the orbital cavity and may compress the nearby structures or erode the orbital walls. Here we report an unusual case of dermoid cyst that mainly involved a bony orbital wall with only a small intraorbital extension.Conclusion: Appropriate diagnosis of unusual cases of dermoid cysts can lead to proper therapeutic approaches and prevention of complications.