The authors present muscle histochemistry of ten patients of multiple sclerosis. The clinical diagnosis was based on criteria established by Poser et al. (1983). The main pathological findings observed were: lymphoplasmocitary vasculitis, increase in the number of 2B type fibers, inflammatory cells (macrophages) in the intramuscular ends of the motor nerves, amounts of lipids and 'moth-eaten' fibers. The presence of vasculitis observed in our cases contributes with the etiopathogenic hypothesis of an autoimune lesion in multiple sclerosis. There is no correlation between the clinical and histological atrophy observed.