Thirty-seven patients with hairy cell leukemia underwent splenectomy. The postoperative course was uneventful for 34 patients. Improvement of peripheral cytopenia was obtained in the majority of patients. Survival time of patients who underwent splenectomy was significantly longer than for patients who did not undergo this procedure. Splenectomy is a habitually effective form of treatment for hairy cell leukemia, although not completely free of risks.