Dermatomyositis is an inflammatory myopathy characterized by muscle weakness and inflammation. In contrast to polymyositis and inclusion body myositis, humoral immune mechanisms appear to contribute to the pathogenesis of dermatomyositis. A 56-year-old man with dermatomyositis resistant to conventional therapies was treated with 6 weekly infusions of the anti-CD-20 monoclonal antibody, rituximab, at a dosage of 100 mg/m in addition to other agents. The patient demonstrated a remarkable clinical response as indicated by an increase in muscle strength and a decline in creatine kinase enzymes. B-cell depletion therapy with rituximab used alone or in combination with other immunosuppressive therapies may be a viable option in patients with dermatomyositis as well as other autoimmune diseases refractory to current therapies.