As a result of the increasing accuracy in diagnosing acute pulmonary embolism by isotopic ventilation-perfusion scintigraphy and pulmonary arterial angiography, the electrocardiographic changes associated with acute cor pulmonale are being abandoned as a diagnostic tool for this life-threatening disease. Nevertheless, certain electrocardiographic findings can raise the suspicion of pulmonary embolism. In our view the electrocardiogram does have some merits in the emergency work-up of a patient with a high suspicion of pulmonary embolism. In this case report we emphasize the importance of the electrocardiographic findings which forwarded the diagnosis of pulmonary embolism. Hence the necessary invasive diagnostic and therapeutic measures, i.e. pulmonary arterial angiography and thrombolytic therapy, can be taken immediately after admission to the emergency department.