Chronic inflammatory demyelinating polyneuropathy (CIDP) is a slowly progressive disabling neuropathy characterized by subacute onset of muscle weakness, distal sensory deficit, elevated spinal fluid protein, and slow nerve conduction velocity with or without conduction block. A monoclonal gammopathy is at times present in the serum of some patients. Because immune-mediated mechanisms against peripheral nerve myelin are thought to be primarily responsible for the clinical manifestations of CIDP, the treatment of choice is with corticosteroids, plasmapheresis or immunosuppressive drugs. Although many patients initially respond to these agents, a large number of them become resistant or develop unacceptable side effects that necessitate their discontinuation. The need for a more effective and safe immunotherapy in CIDP patients prompted the present study using high-dose intravenous immunoglobulin (IVIg). IVIg is an immunomodulating agent which has been recently shown to be effective and safe in the treatment of a number of patients with immune-related neuromuscular diseases.