Meningiomas, one of the most common neoplasms of the central nervous system, may be encountered incidentally during autopsy. Most of these tumors, however, are benign and hence, are not considered as the chief cause of death. Further, sudden unexpected death caused by meningioma is very unusual. Moreover, the diagnosis of an incidental meningioma as the cause of sudden death may sometimes be difficult. In the present report, we describe an autopsy case of a sudden, unexpected death due to a large olfactory groove meningioma accompanied by severe cerebral edema and tonsillar herniation.