We compared the diagnostic sensitivity of magnetic resonance imaging (MRI) and evoked potential (EP) studies in a series of 19 children affected by clinically definite (16 cases) and laboratory supported (3 cases) multiple sclerosis (MS). MRI revealed abnormal areas consistent with demyelinating plaques in 18 out of 19 cases: multiple lesions in 16 and an isolated lesion in 2 cases. Abnormal areas were more frequently found in supratentorial regions than in other areas of the central nervous system. In all patients, the distribution, form and topography of the lesions were typical of MS and similar to those found in the adult form of the disease. Multimodal EP were abnormal in 16 out of 19 cases. Visual (VEP) and somatosensory evoked potentials (SEP) abnormalities were frequently asymptomatic and VEPs were particularly sensitive in ascertaining childhood MS. MRI was slightly more sensitive than multimodal EP in confirming the clinical diagnosis of childhood MS. However, in suspected or probable MS with normal MRI, VEPs and SEPs may contribute to the definition of clinical diagnosis because of their capacity to demonstrate asymptomatic involvement in central nervous system (CNS) the optic nerve and central somatosensory pathways).