Human T-cell lymphotropic virus-I (HTLV-I)-related adult T-cell leukemia/lymphoma (ATL) is a model disease for proof of viral oncogenesis. HTLV-I infection is endemic in southern Japan and the Caribbean basin, and occurs sporadically in Africa, Central and South America, the Middle East, and the southeastern United States. ATL occurs in only 2% to 4% of HTLV-I-infected people [1-3]. When it does occur, it is usually aggressive and difficult to treat; most people survive for less than 1 year [1-3]. Combination chemotherapy with cytotoxic agents has yielded complete response rates of 20% to 45%, but responses usually last only a few months [3]. Recently, novel treatments, such as monoclonal antibodies directed at the interleukin-2 receptor and the combination of interferon alfa and zidovudine, have been shown to be active in the treatment of patients with ATL. A small percentage of patients achieve long-lasting remissions [2,3].