A case of lymphocytic adenohypophysitis presenting as a pituitary tumor is reported. This 30-year-old woman, gravida 1, sought medical attention during the eight month of pregnancy because of progressive headache and bluring of vision and scintillations across both visual field. After delivery, her symptoms were progressive. A large round shaped homogeneous enhancing sellar mass, as a pituitary tumor, was hoswn on brain CT and contrast enhanced MR imaged. Total removal of the tumor was done via subfrontal approach without further neurologic deficit. The tumor was diagnosed as lymphocytic adenohypophysitis with H & E staning postoperative hormonal therapy was performed.