AbstractSplenectomy is highly successful in reversing hypersplenism associated with myeloproliferative disorders (MPD). Significant improvement in leukocyte, platelet, and erythrocyte counts usually occurs within 1 week of splenectomy. Relief of symptoms associated with progressive splenomegaly seen with these entities is also achieved by splenectomy. Splenectomy, however, does not affect the inexorable course of these MPD, which appear to be caused by repeated damage to the pluripotential hematopoietic stem cell population. Hypercellular and hypocellular responses to this bone marrow injury result in a variety of disease states. A review of 50 patients treated with splenectomy for MPD from 1967 to 1980 demonstrated that the operation can be performed with a low mortality rate and minimal morbidity. About 15% of those patients presenting with MPD required splenectomy. Preoperative radionuclide ferrokinetic and sequestration studies, while good predictors of hematological response to splenectomy, do not provide information that impacts on the eventual outcome of splenectomized patients. Selection of patients with MPD for splenectomy is best made on clinical grounds.