We report a patient with longstanding Behçet disease who presented sudden onset of headache and facial paresis. The magnetic resonance imaging (MRI) showed a mass in the right thalamus, extending to the lentiform nucleus, subthalamic area, right cerebral peduncle and deep subcortical white matter. Stereotactic brain biopsy disclosed gliosis with no signs of malignancy. The diagnosis of a pseudotumoral form of neuro-Behçet disease was done and she was treated with pulse methylpredinisolone and intravenous cyclophosphamide. After 8 weeks she had improved and a new MRI showed disappearance of the tumor-like lesion. The differential diagnosis, especially with central nervous system tumor is emphasized.26577-80