Wellens syndrome is a comprehensive electrocardiographic (ECG) diagnosis that combines medical history with characteristic ECG changes. These changes, characterized by biphasic T-wave inversions or symmetric and deep T-wave inversions in the anterior precordial leads, often indicate that the left anterior descending coronary artery is at a high risk of severe stenosis. Chemotherapy-related cardiovascular toxicity refers to damage to the cardiovascular system caused by chemotherapeutic drugs, which is unpredictable and may occur during or after chemotherapy.In this case report, a 41-year-old male patient with cholangiocarcinoma received sequential adjuvant chemotherapy with gemcitabine/nanoparticle albumin-bound paclitaxel and gemcitabine/cisplatin. This patient presented with recurrent brief chest pain episodes after the third dose of gemcitabine/cisplatin, and the characteristic T-wave morphological changes were captured in routine ECG monitoring prior to the 6th dose.Acute coronary syndrome due to chemotherapy-related cardiovascular toxicity was diagnosed on the basis of characteristic ECG changes.The patient underwent coronary angiography, which revealed diffuse stenosis of up to 95% in the middle segment of the left anterior descending coronary artery. Stents were implanted in the stenotic segment for vascular reconstruction.The patient's chest pain was completely resolved, and electrocardiography returned to normal.Cardiovascular toxicity during chemotherapy in patients with cancer may be life threatening. This rare case highlights the importance of identifying the characteristic ECG pattern of the Wellens syndrome by monitoring electrocardiography during chemotherapy. Immediate and accurate identification of the morphological ECG features of Wellens syndrome with a slight elevation of the ST-segment is related to patient prognosis.Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.