Chronic transfusion therapy with the goal of maintaining a hemoglobin (Hb) S <30% is the primary recommended treatment for children with sickle cell anemia and a history of overt stroke or abnormal transcranial Doppler examination. We report chronic hypersplenism as a cause of poor HbS% control in 3 children on chronic transfusion therapy for stroke prevention. Splenectomy resulted in a 39.77% (95% confidence interval, 34.3-45.3, P<0.0001) mean reduction in HbS% with no perioperative or infectious complications suggesting the need for additional research into splenectomy as a therapeutic option for select high-risk children to optimize transfusion therapy for stroke prevention.