The case which is presented here has been hospitalized twice previously, with a diagnosis of schizophrenia; the first to be seven years and the second to be one year ago. Although satisfactory improvement in the symptoms of psychosis was obtained in the second month of third hospitalization, symptoms like ataxia, hypotonia, drop attacks and dysphagia occurred. As EEG and cerebral and cerebellar CT seans were reported as demonstrating no anomaly. multipl sclerosis became a probable diagnosis to explain the emerging sympoms. But signs found on cranial MRI were consistent with Chiari-1 malformation. Symptoms due to Chiari malformaton were absent after the surgical decompression.