A study of purified myelin samples from normal‐appearing white matter of 10 multiple sclerosis (MS) brains was undertaken and the results were compared with 10 age‐matched control brains. Statistical evaluations were carried out with Student's r‐test for differences. In pathological samples the yield of myelin came to only two‐thirds of the corresponding controls. Enzyme assays of the 2′, 3′‐cyclic 3′‐phosphohydrolase revealed an obviously significant reduction of specific activity to one‐half in MS myelins. In myelin the contents of protein, lipid classes as cholesterol, glycolipids and phospholipids did not differ significantly. No cholesterol esters or any lysophospholipid were detectable either in MS or in controls. Within the individual phospholipids the main components were in the same order, while a significant decrease of the acidic representatives and of sphingomyelin occurred. Analysis of the fatty acid pattern of phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylethanolamine (PE), including the aldehydes from the last, revealed quite similar values with no significant differences, except C22: 4 fatty acid in the PE fraction and C20: 1 fatty acid in PS, which were reduced in MS myelin samples.

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