A 34-year-old man who for two months had experienced headaches and blurred vision showed a 6x5x4cm-sized sellar and suprasellar mass with mainly cystic and partially solid portions on both brain CT and MRI. Peripheral, rim-like calcification of the cystic mass was clearly visible on non-enhanced CT and pituitary acidophil stem celladenoma was confirmed. This is an immature neoplasm which is shown by immunohistochemical study and electromicrocopy to be derived from the common progenitor of growth hormone and prolactin cells. We recently encountered one case, involving unusual radiographic findings, in which pituitary macroadenoma mimicked craniopharyngioma, and we report the CT and MR findings of this tumor.