Intravenous immunoglobulin (IGIV) therapy is generally considered to be a safe and effective treatment for idiopathic thrombocytopenic purpura (ITP). The usual initial treatment dose is 1-2 g/kg body weight, which results in an extended infusion time, significantly impacting patients' day-to-day activities. Two crossover studies assessed the safety and tolerability of a novel IGIV preparation (IGIV-C; Gamunex®, 10%) when infused at rates ranging from 0.08 mL/kg/min (the standard maximum licensed rate) to 0.14 mL/kg/min in patients with ITP. The first study included 28 patients and 3 infusion rates; 0.08, 0.11, and 0.14 mL/kg/min. The second study included 8 patients and 2 infusion rates; 0.08 and 0.14 mL/kg/min were evaluated. The incidence of infusion-related adverse events was similar for all infusion rates. Headache was the most commonly reported infusion-related adverse event. The incidence, combined for Studies 1 and 2, was 14.7% (n= 34), 18.2% (n= 22), and 19.4% (n= 31) of patients, for each infusion rate of 0.08, 0.11, and 0.14 mL/kg/min, respectively. The majority were mild in severity. None of the other drug-related, treatment-emergent events were serious; most were mild, in spite of the higher rate of fluid loading over a shorter period of time for patients infused at 0.14 mL/kg/min. There were no clinically important changes in parameters that distinguished between infusion rates; there were no signs of hemolysis. The results suggest that IGIV-C infused at rates up to 0.14 mL/kg/min in patients with ITP is well tolerated.