We report 2 patients with scleromyxedema, both associated with IgG-λ paraproteinemia, who were treated with high-dose intravenous immunoglobulin (hdIVIg) 2g/kg per month. The response to treatment was assessed using an objective skin scoring system initially established for patients with scleroderma. This system grades the overall severity of the induration and the reduction in mobility of the skin. Both patients initially had a dramatic response to treatment which was sustained in one patient. The first patient, a 30-year-old black man, showed a reduction in skin scores from 36/60 to 11/60 over a 3-month period, during which time he had 3 infusions of hdIVIg. After an unplanned 2-month break from treatment, severe neuromuscular complications developed. These improved initially with more frequent infusions of hdIVIg but oral corticosteroids were required to treat worsening myopathy. Unfortunately, the initial response to hdIVIg has not been sustained and his skin scores at 1 year returned to baseline. The second patient, a 60-year-old white man, showed a similarly dramatic reduction in skin scores from 36/60 to 15/60 over a 3-month period after having received only 2 infusions of hdIVIg. There has been sustained improvement after 10 months of therapy and the interval between hdIVIg infusions has been increased to 10 weeks without deterioration. HdIVIg may be an effective treatment for some patients with scleromyxedema, a rare condition with few effective treatments and a poor prognosis. (J Am Acad Dermatol 2000;43:403-8.)