The neurological complications of Behçet's syndrome have not been characterized with clarity. We present the clinical features, imaging characteristics and CSF findings of a series of 50 patients seen at the National Hospital for Neurology and Neurosurgery over the past 10 years. In this series, vascular complications had a low prevalence, whereas involvement of the brainstem was common; spinal cord lesions, hemisphere lesions and meningoencephalitis also occurred. Optic neuropathy, vestibulocochlear and peripheral nerve involvement occurred, but were rare. The prognosis for recovery was in general good, and the majority of those followed-up over a median of 3 years (range 1-19 years) had only single attacks. One-third of patients underwent further attacks, and four underwent progressive deterioration leading to disability. Factors suggesting a poor prognosis are repeated attacks, incomplete recovery, progressive disease course and a high level of CSF leucocytosis during acute attack. These data should be of help in the further definition of the clinical characteristics of this rare neurological disorder and in the planning of treatment trials.