The case history of a 71-year-old woman with three episodes of a microangiopathic hemolytic anemia over a 22-year span is detailed. During the last episode a possible response of her thrombotic thrombocytopenic purpura (TTP)-like syndrome to the administration of intravenous immunoglobulin is documented. In retrospect it became apparent that she only improved in her prior episodes after receiving plasma-containing blood products. Prior case reports of TTP responses to intravenous immunoglobulin are reviewed with specific attention to the dosage used. Since a prospectively randomized series is unlikely to be reported, investigators should be encouraged to report their experience with intravenously administered gamma globulin.