It is rare that unilateral midbrain stroke causes only conjugate upward gaze palsy. There is no reports about the symptoms caused by cerebral endovascular treatments.Case presentation: A 44-years-old female presenting with basilar tip aneurysm received coil embolization. She rapidly developed postoperative narrowing of right palpebral fissure, skew deviation and conjugate upward gaze palsy. Other neurologic symptoms were not seen. Diffusion weighted magnetic resonance revealed small infarction in unilateral midbrain. The symptoms improved two weeks after the procedure. Conclusion: A case of conjugate upward gaze palsy due to unilateral midbrain infarction was observed post coil embolization of the basilar artery aneurysm. As this is a rare complication of endovascular therapy, involvement of an unknown mechanism for conjugate upward gaze is suggested.