Seven patients with adult T-cell leukaemia/lymphoma (ATL) were treated with a combination of zidovudine (AZT) and interferon after failed chemotherapy. One patient showed a major response for nine months. The remainder showed progressive disease further complicated by drug toxicity. The poor responses could be explained by patient selection, since most patients had advanced disease refractory to chemotherapy. A larger more protracted study is required for further evaluation of this treatment option.