A 62-year-old woman was admitted because of leukocytosis, systemic lymph node swelling and erythroderma. Laboratory data disclosed a WBC count of 15,600/microliter (CD4-positive cells: 91%). CD25 and HTLV-1 were negative. A skin biopsy revealed the involvement of T cells. These data and findings were consistent with a diagnosis of Sézary syndrome. Although the patient was treated with 2 courses of CHOP, the leukocyte count did not decrease. We then treated the patient orally with etoposide (25 mg/day) and methotrexate (10 mg/week), and this resulted in reduction of the leukocyte count and lymph node swelling, and amelioration of the erythroderma. As Sézary syndrome is an extremely rare disease, it is worthwhile reporting cases like the present one, where therapy was successful.