The diagnosis of olivopontocerebellar atrophy (OPCA) was previously based on postmortem pathological findings. Recently, however, the various gross anatomical changes of the central nervous system can be defined by the high resolution CT sean, which can make a diagnosis of several degenerative diseases on a clinical basis. This report analyzes 15 cases who showed significant pontocerebellar degeneration on the CT brain scan, including 5 cases of serial studies. All cases were Korean and onset was between 31 to 63 years of age with about 3 time female preponderance. Two patients were in one family suggesting hereditary process. The initial symptoms were ataxic gait, dysarthria, paraparesis, dizziness, and tremors in orders. On examination, the most common clinical maifestations were dysarthria (80%), cerebellar dysfunctions (73.3%) and hyper-reflexia (73.3%). Other findings included parapresis, nystagmus, pathological reflexes and hemiparesis. Characteristically, there were no sensory or mental deficits. The progression of the symptoms tended to parall the CT scans on serial studies. The evoked potential studies including brainstem auditory evoked potential revealed no significant abnormalities exept one case who showed only borderine prolongation of interwave latency between wave 1 and 3. The responses on antiparkinson regimens were fruitless.