MBP was isolated and purified from bovin spinal cord as described by Deibler. A sensitive and specific RIA was used for quantitatiag the lavel of MBP in tie CSF samples which was collected from 106, patients with various neurological diseases. In the funetional headache group, the mean level of MBP in CSF was 3.0 ? 2.24ng/ml, so the upper control level of CSF MBP was 7.48 ng/ml (X+2SD). The mean level of MBP in CSF of 33 patients with MS was 21.98?11.82 ng/ml. Thirty-one cases had elevated level of CSF MBP (93.94%). The CSF MBP level of MS patients was significantly higher than the level of patients with sporadic encephalitis, other neurological diseases, and headache (p