Earlier reports on T2-weighted magnetic resonance imaging (MRI) in the classical form of Pelizaeus-Merzbacher disease seemed to divide the patterns of the high-intensity lesions in the white matter into three subtypes: type I, diffusely hemispheric and corticospinal; type II, diffusely hemispheric without brainstem lesions; and type III, patchy in the hemispheres. The four boys presented in our study, between 10 and 17 years of age, with classical Pelizaeus-Merzbacher disease, who all had a duplicated proteolipid protein gene, invariably manifested type I despite their various clinical severities. Follow-up MRI after an interval of 5 years and proton magnetic resonance spectroscopy was performed in three of the patients. The white matter on the last MRI was unchanged in volume and the distribution of high-intense areas. Proton magnetic resonance spectroscopy revealed no abnormal peaks. These results were consistent with the lack of definite neurologic regression in the last 5 years and with the pathologic characteristics of well-preserved axons and the absence of sclerosis. Further study is required to precisely determine whether the patterns of MRI findings can be divided into subtypes corresponding to those of proteolipid protein gene abnormalities.