Giant mucoceles of the frontal sinus are rare but their recognition is important in the differential diagnosis of proptosis and fronto-orbital lesions. The authors describe a patient with frontal giant mucocele with intracranial as well as orbit and ethmoid sinus involvement. Thirty-two years after a frontal sinus fracture, a 51-year-old female presented with headache, and left exophthalmos and ophthalmoplegia. Computed tomography and magnetic resonance imaging demonstrated a giant frontal sinus mucocele with extension into the left anterior cranial fossa. The mucocele was treated with a transcranial and endoscopic transnasal approach. The frontal sinus was then cranialized with reconstruction of the posterior wall, and finally a wide nasal drainage was performed. The clinical symptoms disappeared immediately after surgery.