Abstract Authors describe an intradiploic epidermoid cyst of the parietal bone with intra and extracranial extension. A 23-years old male patient with a history of subcutaneous swelling 3 months ago on the right parietal scalp. CT and MRI evaluation revealed a well defined extracerebral mass in the parietal scalp with destruction of both the inner and outer tables of the calvaria. The patient underwent a total resection of the tumor and the histological examination suggesting a epidermoid cyst. The patient post-operative course was uneventful, without any neurological deficit. Intradiploic epidermoid cysts of the skull are rare, slow growing, mostly benign tumors. The prognosis is good when the cyst is totally resected with its capsule.