High-dose intravenous immunoglobulin (IVIG) is considered a safe and efficacious treatment for patients with a variety of hematological and non hematological diseases, including patients with idiopathic thrombocytopenic purpura (ITP) not responsive or with contraindications to corticosteroids and/or splenectomy. Side-effects are usually minor, but severe reactions have been rarely reported. We describe the case of a patient with ITP, without pre-existing renal disease, who developed a severe transitory acute renal failure following administration of IVIG, promptly reversed after hemodialysis.