The prognosis of angioimmunoblastic T cell lymphoma (AITL) is poor because of chemotherapy-resistance and the short duration of remission. In recent years, cyclosporin A (CyA) has been employed as a alternative treatment for AITL in some patients with the rationale that CyA inhibits the activity and proliferation of neoplastic T cells. We herein report 4 chemotherapy-resistant AITL patients who were treated with oral CyA. The dosage of CyA was individually determined in each patient in order to achieve a blood CyA concentration of around 200 ng/ml at the trough level. A patient in whom AITL had relapsed 3 months after high dose chemotherapy with autologous hematopoietic stem cell transplantation (HSCT) achieved a sustained complete remission (CR) with CyA and underwent allogeneic HSCT. In 2 patients who had failed to respond to conventional chemotherapies, the circulating lymphoma cells rapidly disappeared after the initiation of CyA, and one of these patients demonstrated a durable CR. The other patient showed a good response to CyA, but the agent was discontinued because of infection. The remaining one patient with advanced AITL did not respond to CyA and died of disease progression. To our knowledge, the efficacy of CyA for chemotherapy-resistant AITL, even in a leukemic state, has not previously been reported.