BACKGROUND: Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by increased platelet count and risk of thrombosis and bleeding, which necessitates careful perioperative management. However, there are no standardized guidelines for perioperative antithrombotic therapy, and optimal preoperative evaluation remains unclear. In this report, we evaluate the utility of thromboelastography (TEG®6 s) for assessing coagulation and platelet function in ET patients undergoing surgery. CASE PRESENTATION: Four ET patients (platelet counts: 289,000-833,000/µL) underwent thromboelastography at anesthesia induction. Two had normal coagulation, while two had a hypercoagulable state undetected by conventional tests. Hypercoagulability was observed in patients who discontinued anticoagulants or antiplatelets preoperatively. CONCLUSIONS: Thromboelastography identified thrombotic tendencies not evident with conventional coagulation tests, suggesting its potential for perioperative risk assessment in ET patients. This approach may improve individualized coagulation management beyond use of platelet counts and standard tests. Further studies are needed to establish the role of thromboelastography in optimizing perioperative antithrombotic strategies.