The long-term outlook for patients with HCL has brightened over the last 5 years with the development of two highly effective systemic therapies, pentostatin and alpha-interferon. Pentostatin can induce complete responses in over 75 per cent of patients and may offer cure in this disease. Splenectomy continues to have a role as first-line therapy in selected patients in whom it may offer a median remission duration of over 5 years. Alpha-interferon is the treatment of choice for patients requiring initial systemic therapy and can be used intermittently to re-induce remission in patients with disease progression off therapy. Outside of clinical trials pentostatin should be utilized only in appropriately selected patients refractory to interferon therapy.