We investigated the prevalence and type of neurologic involvement in Behçet's syndrome in a prospective protocol. Of 323 consecutive patients with Behçet's syndrome seen during a 12-month period, 46 underwent neurologic evaluation because of headaches and/or neurologic symptoms and signs. Only 17 (5.3%) were found to have involvement of the nervous system. Hemispheric lesions were as common as brain-stem involvement. Headaches were of no clinical importance unless accompanied by other neurologic findings. Computed tomographic scans were of little diagnostic help. After 12 +/- 4 (SD) months of follow-up, only three patients showed worsening of their neurologic findings.