We recently observed a patient in whom basal ganglia calcification (BGC) was demonstrated on sequential CT scans only 9 days after the anoxic episode. A 58-year-old woman had a history of diabetes mellitus for 23 years for which she was treated with insulin. She had a operation for retinal detachment under local anesthesia. Two days after the operation, she developed dyspnea, and was referred to our department. She was intubated, and respiratory support was begun. On neurological examination, she was semicomatose, and intermittent spontaneous movements involved in all extremities. The pupils were 3 mm in diameter, equal and responsive. Full doll's eye responses were obtained both horizontally and vertically. Deep tendon reflexes were hyperactive bilaterally without ankle jerks and extensor plantar responses. Arterial blood gas levels revealed a PaO2 of 49 mmHg, PaCO2 38 mmHg: pH 7.16. Serum Ca, P, Mg, Al-p and parathyroid hormone levels were normal. The EEG was isoelectric. Although the initial CT scan was normal, the subsequent CT scan 9 days later showed extensive high density change of the striatum, which was assumed to be BGC due to anoxia was briefly discussed.