The most common cause of isolated oculomotor nerve palsy is ischemia of the peripheral nerve caused by a disease, such as diabetes mellitus. Another common cause of isolated oculomotor nerve palsy is compression by an intracranial aneurysm, usually an posterior communicating artery aneurysm. However, it is extremely rare in the pituitary tumor. We report an unusual case of pituitary adenoma presenting with isolated oculomotor nerve palsy in the setting of pituitary apoplexy. We suggest that pituitary apoplexy should be included in the differential diagnosis of a patient with isolated oculomotor nerve palsy and early surgery should be considered for preservation of oculomotor nerve function.