This report documents an unusual case of adult T-cell leukemia (ATL) with a preceding phase of long-standing cutaneous involvement. After nine months of an aleukemic phase, characteristic leukemic cells of ATL, possessing inducer/helper phenotype without helper function, had appeared. In addition, antibodies to ATL virus-associated antigen (ATLA) were found in the serum of the patient and her family. The patient died after an 18-month clinical course due to generalized cytomegalovirus infection in spite of strong chemotherapy. At autopsy, leukemic involvement was restricted to the skin. We postulate that ATL may originate not only from the lymph nodes but also from the skin.