The diagnosis of OPCA could be made clinically with important aid of brain CT scanning, although the definite and conclusive diagnosis only by postmortem pathological determination. We reviewed, clinically and with brain CT examination, 12 cases of patients with OPCA who were admitted to the Yeungnam University Hospital for a recent 5 years. The result were as following: 1. The distribution of age is from 49 to 72, mainly 50 to 60. Man is more frequent than women at the 4.5 times. 2. The interval period from Sx. Onset to diagnosis is 1 year to 6 years. 3. The usual initial Sxs. Were dizziness (58%), ataxia (33%), and other less frequent Sxs. Were weakness of low extremities, dysarthria, headache and urinary incontinence. The clinical manifestations at the initial diagnosis were cerebellar disturbance (100%), dysarthria (83%), and increased deep tendon reflexes (58%). 4. The results of brain CT finding are like this: the width of cerebellar sulci is more than 1mm, other 4 cases more than 2mm. the width of cerebellar pontine cistern of the patient if usually 3 to 4mm, other 2 cases extended to the 5 mm. the A. P and lateral lengths of 4th. ventricle is 4 mm and 4 to 8 mm respectively. 6 cases of whole patients show coincidentally cerebral atrophy.