Hypersplenism is characterized by cytopenia, splenomegaly (possibly hyperplastic bone-marrow), and lienal hypersequestration. It is necessary, in view of the rather important surgical risks of splenectomy, to clarify if the hypersplenism may be influenced by splenic irradiation in case of chronic myeloid leukemia (CML) or chronic lymphatic leukemia (CLL). References in literature are rare and do not present a reliable differentiation of the syndrome, according to its present definition. Of our patients, three cases with hypersplenism verified by radioiron studies are reported: in one patient with chronic myeloid leukemia, irradiation of the spleen had no effect, whereas pancytopenia was completely repaired by means of splenectomy. The same results were seen in a patient with chronic lymphatic leukemia. In the last patient, however, who had chronic lymphatic leukemia, fractionated irradiation of the spleen led to a distinct improvement of anemia and thrombopenia, but the recovery lasted only six months. This effect is due to transient normalization of the lienal hypersequestration.