We report here a case of adult T-cell leukemia (ATL) who presented acute renal failure and skin eruption. Renal and skin biopsies showed diffuse invasion of ATL cells. Furthermore, the surface phenotype of tumor cells taken from the bone marrow (BM) or peripheral blood (PB)(CD4-CD8-) differed from that of cells taken from the kidney or skin (CD4+CD8-). These findings suggested that CD4-CD8-ATL cells in the BM and PB had differentiated to CD4+CD8- cells in the kidney and skin.