Magnetic resonance imaging (MRI) has a pivotal role in diagnosis of multiple sclerosis and is being increasingly used as a paraclinical measure to assess treatment efficacy in clinical trials. However, the correlations between clinical and MRI findings in patients with multiple sclerosis are weak and, therefore, newer MR techniques are being developed to increase both MRI sensitivity for detecting disease activity and its pathological specificity for better assessing disease evolution. Evoked potentials (EPs) can be used to confirm the diagnosis of multiple sclerosis and their abnormalities are correlated with symptoms and signs referable to involvement of the corresponding nervous pathways. However, their use is limited when assessing disease progression and monitoring clinical trials in multiple sclerosis. Both magnetic resonance imaging (MRI) and evoked potentials (EPs) provide information which cannot be obtained by clinical evaluation, especially for assessing disease activity. Nevertheless, both these paraclinical techniques cannot substitute for clinical measures of disability when assessing disease progression and monitoring phase III clinical trials in multiple sclerosis.