OBJECTIVE AND IMPORTANCE:The preservation of oculomotor nerves is one of the most significant issues regarding the resection of meningiomas around the cavernous sinus.CLINICAL PRESENTATION:We report the case of a patient whose oculomotor nerve was fenestrated, caused by a large meningioma around the cavernous sinus. The nerve function remained intact until surgery.INTERVENTION:During surgery, one trunk of the fenestrated nerve behind the tumor was sacrificed. The fenestrated shape of the nerve led us to the misjudgment that the preserved other trunk located along the upper margin of the tumor was the whole nerve.CONCLUSION:Although fenestrated oculomotor nerves may be rare, their possibility should be kept in mind during surgery around the cavernous sinus.