The therapeutic approach to hairy-cell leukemia (HCL) is in some instances still debated. Although management with alpha-interferon and purine analogues is well established, there is an alternative role for therapeutic splenectomy in patients with massive splenomegaly who have failed to respond to systemic therapy. Most patients with HCL will not be suitable for treatment with splenectomy as their ages at diagnosis are high. Here, we report an elderly Japanese HCL patient whose refractory massive splenomegaly responded well to low-dose splenic irradiation.