Abstract Interferon alfa-2a (Roferon ®-A) was given to 20 patients with advanced cutaneous T cell lymphomas, all of whom were heavily pretreated. Objective responses were seen in nine of the 20 patients, including seven partial and two complete responses. The median response duration was 5.5 months, with three of the responses lasting 2 or more years. Toxicity was moderate but was alleviated by dose reductions. These results demonstrate that Roferon ®-A is highly effective in the treatment of advanced refractory cutaneous T cell lymphomas. The role of this treatment in earlier stages of disease and in combination with other standard forms of therapy needs to be evaluated.