The electrocardiogram (ECG) may be entirely normal in the patient with pulmonary embolism (P/E); alternatively, any number of rhythm and/or morphologic abnormalities may be observed in such a patient. The abnormal ECG may deviate from the norm with alterations in rhythm, in conduction, in axis of the QRS complex, and in the morphology of the P wave, QRS complex, and ST segment/T wave. The electrocardiographic findings associated with PE are numerous, including arrhythmias (sinus tachycardia, atrial flutter, atrial fibrillation, atrial tachycardia, and atrial premature contractions), nonspecific ST segment/T wave changes, T wave inversions in the right precordial leads, rightward QRS complex axis shift and other axis changes, S1Q3 or S1Q3T3 pattern, right bundle branch block, and acute cor pulomnale. This review focuses on the ECG and the various abnormalities seen in the patient with PE.