The ability of IVIG to increase platelet counts in patients with idiopathic thrombocytopenic purpura suggests its potential usefulness in other disease states characterized by low platelet counts. This possibility was evaluated in nine patients with the Wiskott-Aldrich syndrome (WAS) who received IVIG, at a dose of 400 mg/kg every 4 weeks. The mean platelet count prior to institution of IVIG was 32,000/cumm (range 2,400 to 98,000). Following administration of IVIG, the platelet count ranged between 5,000 and 85,000/cumm. There were no immediate increases in platelet counts after IVIG infusion in any patient who had serial platelet counts. During treatment, patients were not given any routine platelet transfusions for low platelet counts. However, while on IVIG, two patients showed a good response to platelet transfusion prior to surgical procedures. In conclusion, chronic IVIG therapy does not appear to affect platelet counts in patients with the Wiskott-Aldrich syndrome.