This is the second, completely rewritten edition of the widely acclaimed book on MR of myelin, myelination and myelin disorders (1989). In the last five years many new data became available with regard to genetics, molecular biology, the role of cellular substructures on one side and on the other side regarding the growing experience with MR patterns of less common myelin disorders. Not only, therefore, the text has been updated, but many new chapters have been added on disorders of which previously the white matter involvement was less clear. The acquired myelin disorders were reorganized and their backgrounds were more extensively elucidated, to place the MR examinations in the clinical context where they belong.