Essential thrombocythemia (ET) is a rare myeloproliferative disorder characterized by an unexplained thrombocytosis (>450 × 109/L) and associated vasomotor, thrombotic, and hemorrhagic manifestations. Although the literature detailing the perioperative management of patients with ET undergoing cardiac operations is sparse, major perioperative complications have been reported, particularly in poorly controlled patients presenting with platelet counts of 800 × 109/L or higher. The purpose of this study was to provide the experience at a large tertiary medical center in managing patients with ET undergoing cardiac operation and to summarize the available literature. Patients with ET undergoing cardiac operations between January 1, 2006, and May 1, 2016, were identified. Perioperative data were exhaustively reviewed and recorded. An extensive literature search for "essential thrombocythemia" and "cardiac surgery" was performed. During the study period, 25 patients with ET underwent cardiac operations, and 24 had immediate preoperative platelet counts of less than 800 × 109/L. Perioperative complications related to ET occurred in 1 of 25 patients (4%). The immediate preoperative platelet count was 181 × 109/L. A literature search identified 18 patients who underwent cardiac operations, with major perioperative complications occurring in 5 (28%), of which 4 of 5 had an immediate preoperative platelet count of 800 × 109/L or higher. Patients with ET undergoing cardiac operations represent a complex cohort at risk for perioperative thrombotic or hemorrhagic complications, or both. Although not currently an indication for platelet reduction therapy by risk stratification criteria, preoperative cytoreduction to platelet counts of less than 800 × 109/L and perhaps lower should be considered in patients undergoing cardiac operations.