Matrix metalloproteinases (MMP-) are involved in leukocyte invasion into the central nervous system (CNS) during inflammation. In a retrospective cohort study of 18 neuro-BD patients, CSF samples were studied for MMP-9, TIMP-1 and cell characteristics in neuro-BD patients compared to 12 Headache attributed to BD (HaBD) patients, 15 multiple sclerosis (MS) and 20 Non-inflammatory Neurological Disease (NIND) patients. Concentrations of MMP-9 and TIMP-1 were measured in CSF by using an enzyme-linked immunosorbent assay (ELISA). The MMP-9/TIMP-1 ratio was significantly increased in neuro-BD group (mean +/- SD: 0.145+/-0.045) compared to (HaBD) (0.065+/-0.029; p=0.0001) and NIND patients (0.070+/-0.031; p=0.0001). No significant differences were observed between neuro-BD and MS patients. A significant correlation was observed between CSF-PMN cells and MMP-9 in neuro-BD patients (r=0.714; p=0.0009), indicating probably that PMN cells were in part the source of MMP-9. A significantly positive correlation was also observed between MMP-9 and CSF-mononuclear cells in neuro-BD patients (r=0.623; p=0.0012). This is the first study to evaluate the expression of matrix metalloproteinase-9 and tissue inhibitors of metalloproteinase-1 in cerebrospinal fluid of neuro-BD patients. It demonstrates increased matrix metalloproteinase-9/tissue inhibitors of metalloproteinase-1 ratio. The results suggested that MMPs released in the CSF may be involved in the pathogenesis of neuro-BD by promoting local damage, similarly as suspected in other inflammatory diseases.