We report on a boy with refractory chronic idiopathic thrombocytopenic purpura (ITP) successfully treated with combination therapy composed of low-dose cyclosporin A (CsA), azathiopurine, and prednisolone. The patient was diagnosed as having ITP at 5 years of age, and received high-dose intravenous immunoglobulin (IVIG), followed by oral prednisolone, intravenous pulsed dexamethasone, oral cepharantin, and intermittent IVIG therapies. Because there were no or only transient responses to these medical therapies over 2 years, he was splenectomized. However, 3 months after the splenectomy, his platelet counts fell to below 10 x 10(3)/microl accompanied by wet purpura. We resumed low-dose intermittent IVIG treatment for 1 year without sustained efficacy. We then started combination therapy with CsA (2.5 mg/kg/day), azathiopurine (1.7 mg/kg/day), and prednisolone (0.8 mg/kg/day). Complete remission was achieved within 2 weeks and the platelet counts remained > 50 x 10(3)/microl even after tapering off the prednisolone and azathiopurine at 6 and 12 months, respectively and have moreover remained normal for more than 10 months after completion of 2 years of CsA treatment. There were no adverse events during the therapeutic course. This is the first pediatric case of ITP treated with CsA in Japan. Such combination therapy may be promising and tolerable for childhood ITP with splenectomy failure.