Subjects The patient group (Group 1) will consist of 150 patients with diagnosed MS, recruited at the MS Center of Oregon. For this group, inclusion criteria for each patient will include: (1) a clinical or laboratory supported diagnosis of "definite MS" (Poser, et al., 1983); (2) a diagnosis of relapsing, remitting or secondary progressive MS; (3) A Kurtzke Expanded Disability Status Score (EDSS) of 0 to 7.0, inclusive; (4) no history of a clinical relapse or change in EDSS for three months preceding entry into the study; and (5) a brain MRI scan (within the preceding year) that shows at least three white-matter lesions on T2-weighted images consistent with MS.