The present paper concerns serial examinations of computed tomography (CT) and magnetic resonance imaging (MRI) in 22 patients with sporadic amyotrophic lateral sclerosis (ALS). Supranuclear ophthalmoplegia developed in 13 and dementia in 3 patients. The investigations showed gradually progressive atrophy, first in the frontal and anterior temporal lobes then in the precentral gyrus, and later in the postcentral gyrus, anterior part of the cingulate gyrus, corpus callosum and brain stem tegmentum. MRI revealed high intensity signals on T2-weighted images in the precentral and adjacent gyri, frontotemporal white matter and pyramidal tract as well as rarely in the globus pallidus and thalamus. These neuroradiological changes were not related to the duration of the clinical course or to the degree of the motor impairment. These alterations may play a critical role in the supranuclear ophthalmoplegia seen in ALS patients. The dementia of ALS probably reflects involvement of both the frontotemporal lobes and limbic system.