Seven members of a family with an X-linked spastic paraparesis syndrome were analyzed by MR imaging and stimulated echo, solvent-suppressed proton nuclear magnetic resonance spectroscopy. The MR scans of three symptomatic males and two asymptomatic females demonstrated abnormal signal in the supratentorial white matter. Each of these patients had a proton spectroscopic examination of a 2 X 2 X 2 cm voxel localized to the abnormal white matter of the centrum semiovale. The spectra demonstrated depression of N-acetyl aspartate/creatine, N-acetyl aspartate/choline, and creatine/choline ratios compared with normal control subjects. Additionally, these patients had abnormal elevations of amino acid resonances in the 2.1-3.0 ppm range. In a patient with symmetric white matter signal intensity abnormalities, an asymmetric spectroscopic study correlated with asymmetric symptoms. One asymptomatic family member with a normal MR study had abnormal metabolite ratio measurements. She was referred for further evaluation, since the proton spectrum suggested she may possess the affected gene. If the findings in this study are duplicated in other cases of hereditary dysmyelinating syndromes, we believe the integrated MR/proton nuclear magnetic resonance spectroscopy examination will be of benefit in evaluating and counseling families with familial dysmyelinating disorders.