The inflammatory myopathies are a group of acquired muscle diseases characterized by subacute onset of progressive proximal muscle weakness, elevated serum muscle enzymes and endomysial inflammation. They comprise 3 clinically distinct subsets: polymyositis (PM), dermatomyositis (DM) and Inclusion Body Myositis (IBM). Because immune-mediated mechanisms are primarily responsible for the clinical manifestations of these conditions, the treatment of choice is with corticosteroids or immunotherapy drugs. Although most of the patients initially respond to these drugs, a number of them become resistant or develop unacceptable side effects that necessitate their discontinuation. The need for a more effective and safe immunotherapy in patients with PM, DM or IBM prompted the present study using high dose intravenous immunoglobulin (IVIg). IVIg is an immunomodulating agent which has been shown to be effective and safe in the treatment of a number of patients with immune-related neuromuscular diseases.