Fibrous dysplasia (FD) and aneurysmal bone cyst involving the facial skeleton are rare but their synchronous association in other parts of the body is well-known. The most common treatment for these lesions has been based on surgical resection using an external approach. Only recently has the endonasal endoscopic approach been utilized for the partial or complete removal of these lesions. In this report, we attempt to outline the effectiveness of the endonasal endoscopic approach for the treatment of a 5-year-old child affected by a fibrous dysplasia associated with an aneurysmal bone cyst of the right maxillary.