We present a rare case of intracranial mucocele associated with frontal sinus osteoma in a patient suffering from generalized convulsion. The intracranial mucocele occurs as a complication of obstruction of sinus drainage caused by osteoma, but it is often diagnosed preoperatively as an intracranial or intracerebral cyst because of the rarity of these combined lesions in neurosurgical practice. However, once the mucocele extends intracranially, several other complications, including infections and/or a convulsion, can occur, indicating the necessity for surgical treatment. Moreover, the differentiation of the mucocele from the intracranial endodermal cyst predominantly depends upon its continuity with the intracranial osteoma portion or the sinus. Thus, knowledge of this rare lesion is important for accurate diagnosis and clinical management.