MS is a chronic, inflammatory, demyelinating disease of the CNS. It is characterized bylesions in especially the white areas of the brain. The immunological mechanisms are notcompletely recognized.Intrathecal IgG-production is associated with MS. Oligoclonal IgG-bands are pathologicalfindings, but it is not specific. T-cells are also very involved in the patogenesis of MS, buttheir role is not completely understood. Macrophages are the dominating cell type in activeMS-lesions.We used CSF samples from 51 patients under investigation for MS. The samples werealready processed with flow-cytometria for cell counts.We studied the patients’ journals and classified them into MS and controls. The patients wereclassified according to type of MS and EDSS.The most interesting findings were in the monocyte population. Percentage of highlyactivated monocytes were lower in MS-patients than in controls, and the low activatedmonocytes were higher in MS-patients than in controls, though these findings were notstatistically significant.We found nearly significant findings for the index highly activated monocytes/low activatedmonocytes. Future studies should aim to see if this index, combined with the numbers of eachvariable in the index might be used as a diagnostic marker.