Immunoblastic lymphadenopathy (IBL)-like T-cell lymphoma is considered to belong to peripheral T-cell lymphoma. Its prognosis is grave and effective treatments have not been established. Recently, we gave oral cyclosporin A (CsA) to a patient with IBL-like T-cell lymphoma, and succeeded in achieving dramatic remission. In this case, serum levels of interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNF alpha) were elevated and decreased or returned to normal after achieving remission. Since CsA is a potent suppressor of the immune system and most notably T-cells, the immunosuppression of T-cell function might have played an important role in achieving remission in this case, although the precise mechanism still remains to be elucidated. The present case indicates that administration of CsA may be a very effective and safe selection of therapy for IBL-like T-cell lymphoma, as well as analogous disorders such as IBL and angioimmunoblastic lymphadenopathy with dysproteinemia (AILD), thereby will contribute to improving the prognosis of patients with these diseases.