This is a preliminary report of studies, by means of the ultracentrifuge technic, of certain lipoproteins (those which sediment at a rate between 12 x 10-13 and 20 x 10-13 cm./ sec. under the influence of a unit field of force in a soln. of specific gravity 1.063 at 26[degree]C) in the cerebrospinal fluid of 14 multiple sclerotic patients, and in the serum of 27 such patients. The lipoprotein level in cerebrospinal fluid was too low to be measured by the ultracentrifuge technic. A suggestive increase in serum lipoprotein was observed in cases of multiple sclerosis during acute phases of the disease. If confirmed, this increase may reflect a primary disturbance in the lipoprotein metabolism underlying the disease, or, less likely, may be a secondary effect, resulting from the activity of the disease.