We present serial clinical, radiological and neurophysiological findings of a patient with late-infantile metachromatic leukodystrophy (MLD), who was first admitted to the hospital at the age of 30 months, because of gait disturbance; neurologically he showed the picture of a mild spastic diplegia. Magnetic resonance imaging (MRI) disclosed diffuse high intensity in the cerebral white matter on Til-weighted images. Nerve conduction velocities and evoked potential studies were markedly abnormal. Assay of arylsulfatase A activity in leukocyte culture disclosed a marked deficiency of the enzyme, thus confirming the diagnosis of late-infantile MLD. Serial neurophysiological and MRI studies demonstrated the progressive nature of the disorder, correlating with the clinical deterioration (spastic tetraplegia with optic atrophy and epilepsy).