The causes of pituitary apoplexy are unclear. We report a case of pituitary apoplexy presenting with headache and nausea. On June 17th, 1997 a 74-year-old woman had complained of retro-orbital headache, fever and vomiting. A cold was diagnosed for which she recurred medication. In addition to the previous symptoms she was getting to lose appetite. She was admitted to our hospital for further examination and treatment on June 21. On admission neurological examination showed left pupil mydriasis, the left eye had no light reflex and the right eye had only a slight response to the light. She could hardly move both eyeballs up. Laboratory data showed a normal white blood cell count and the CRP was 16.2 mg/dl. Lumbar puncture showed 97 mg/dl total protein and 82 cells per microliter, most of which were lymphocytes. We diagnosed viral infection based on the evidence of clinical symptoms and lumbar puncture data. The patient was treated with gamma-globulin and improved. From the 16th day of sickness we recognized symptoms of oculomotor paralysis and the syndrome of inappropriate antidiuretic hormone. On the 23rd day of sickness we strongly suspected pituitary apoplexy based on transaxial MR images. After absorption of intra-tumor hemorrhage, the oculomotor symptoms recurred. We finally reached a diagnosis of pituitary apoplexy based on pathological material, MR images, symptoms and laboratory data. We must think of pituitary apoplexy when we see an aged out-patient with severe headache, nausea, vomiting and oculomotor paralysis. It was difficult to diagnose this disease in the early time course of the disease.