Pituitary apoplexy, the sudden infarction, necrosis of hemorrhage into a pituitary adenoma may be threatening life and is difficult to diagnose. With an advent of Computed Tomography (CT), early diagnosis of hemorrhage into the pituitary adenoma is possible if one has familiarity with its characteristic CT changes. Two cases of pituitary apoplexy are reported with brief review of the literatures. One case had a history of radiation therapy for pituitary adennoma 7 years age, and the other had no symptoms or signs of pituitary tumor prior to onset of disease.