Abstract： To the Editor:Ophthalmoplegia can cause diplopia,with a lot of etiologies including cerebrovascular disease.Nuclear ophthalmoplegia resulted from brainstem infarction is often accompanied by other symptoms of brainstem dysfunction.It is fairly rare that midbrain infarction only manifests as isolated medial rectus nuclear palsy.[1] Here,we provided such an uncommon case and discussed the possible etiology.