The intravenous immunoglobulin infusion therapy (IVIg) has recently acquired an important role in the treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Some patients, however, require repetitive infusions to maintain the improvement. We planned a one-day therapy with 0.4 g/kg of IVIg in every 7 or 10 days for two CIDP patients who had required a 5-day course of IVIg in every month because of frequent exacerbations. Serum levels of IgG in both patients were kept as high as 2,000 mg/dl resulting in maintaining the improvement without any side effects.