Sézary syndrome has been described as the leukemic form of cutaneous T-cell lymphoma, defined by the presence of CD4(+) T-cells with cerebriform nuclei in the peripheral blood, erythroderma and lymphadenopathy with occasional involvement to lymph nodes, and visceral organs according to course. We report a 48-year-old woman with Sézary syndrome. Most of peripheral blood mononuclear cells (PBMC) showed CD4(+), CD7(+) surface marker while infiltrating cells to the skin consisted of the same percentage of CD4/CD8 cells. CD4(+) cells predominantly expressed IL-8 both in PBMC and the skin, and generated significant amount of IL-8. In contrast, lesional keratinocytes showed only a trace amount of IL-8 when compared to strong expression by infiltrating CD4(+) and CD8(+) cells. These studies suggested that leukemia cell-derived cytokines such as IL-8 might play some role in the induction of erythrodermic features of Sézary syndrome.