Among 110 patients (45 men, 65 women), aged 15 to 66, with clinical and/or biological diagnosis of multiple sclerosis (MS), severe to moderate corpus callosum (CC) atrophy was observed in 67 (60%) patients. Correlation between CC atrophy, brain atrophy, duration and severity of clinical symptoms, and high signal white matter areas, was carried out in 90 patients. Mean age was 46 years for patients with severe CC atrophy, and 33 years for those without atrophy. Mean duration of the disease was 14 years in patients with severe atrophy, and 5 years in patients without atrophy. Severity of clinical symptoms is more pronounced in patients with severe CC atrophy. Numerous or large white matter high signal areas are observed in patients with severe CC atrophy on T2-weighted images. CC atrophy appears earlier than brain atrophy in the course of MS.