Combination therapy with interferon-α and zidovudine (IFN/AZT) has been regarded as standard care for acute and indolent (i.e., chronic and smouldering) ATL based on reports involving a limited number of patients. This treatment approach has not been evaluated in Japan, a major endemic area of this disease in the world. This is the first Japanese report of IFN/AZT for ATL. It is impossible to draw any definitive conclusion from this small study; however, IFN/AZT showed clear anti-ATL effects for refractory/relapsed ATL patients. This report would contribute for developing future ATL treatment in Japan.