Magnetic resonance imaging (MRI) of the brain, neck and cervical spine of five patients with the mild variant of Hunter's syndrome (iduronate sulphate sulphatase deficiency, mucopolysaccharidosis Type II, MPS II) are described and compared with the few available reports in the literature. The most prominent abnormalities in the brain include ventriculomegaly and brain atrophy, the presence of well defined cystic areas of decreased signal on T1- and increased signal on T2-weighted images, of the thalamus, basal ganglia and brain stem, and decreased signal on T1-weighted and increased signal changes on T2-weighted sections of the periventricular and subcortical white matter. A giant cisterna magna was present in four patients and a J-shaped sella in three. Thickening of the soft tissue posterior to the odontoid peg was present with associated canal stenosis in all cases resulting in compression of the cervical cord in four cases. All patients had ill-defined decreased signal on T1-weighted and increased signal changes on T2-weighted sections within the cord. In some, this was associated with cord expansion. Airway narrowing was a common finding. Disc dehydration and the classical platyspondyly with antero-inferior beaking of the vertebral bodies was seen.