A 14-year-old girl with chronic idiopathic thrombocytopenic purpura (ITP) presented in relapse with a platelet count of 1,000/μUL and a high-level serum antiplatelet IgG antibody. She previously had been unresponsive to courses of therapy with steroids, vincristine, and splenectomy. When treatment with danazol and purified immunoglobulins was unsuccessful in controlling her rapidly progressive course, an 8-day plasma exchange procedure was initiated in combination with platelet transfusion therapy and immuno-suppression with cyclophosphamide and vincristine. Within 2 days, her clinical state improved markedly, correlating with a drop in her serum antiplatelet antibody level. She continued to improve and was discharged on a regimen of cyclophosphamide and danazol. Her antiplatelet antibody level had fallen to within the normal range, despite a typical platelet count of 5,000/μL during the 8-day period. Two weeks later her platelet count rose to 65,000/μL. This case suggests that a course of therapeutic plasma exchange may have a temporizing role in the acute management of life-threatening chronic ITP relapse, generating time for the more definitive therapy of immunosuppression to take effect.