Background: Objective diagnosis of severe pulmonary embolism (PE) is obligatory because of its considerable mortality. Aim: To assess the abilities of electrocardiography (ECG) score (sECG) and the newly generated scoring system composed of the scores obtained from arterial blood gas (ABG) analysis and shock index (SI) in addition to sECG in predicting severe PE. Material and Methods: The degree of pulmonary vascular obstruction (sPVO) and the right ventricular dysfunction (RVD) were determined with spiral computed tomography (CT) in 53 consequent patients with PE. Twelve-lead ECG taken within a day of PE event and ABG values were evaluated according to ECG scoring system and original Geneva system, respectively. Results: The mean age of patients was 62.6 +/- 13.4 years. Right ventricular dysfunction, sPVO >= 50%, hypoxemia, and SI were present in 34 (64.2%), 27 (50.9%), 50 (94.3%), and 22 (41.5%) patients, respectively. The mean sECG, 5.9 +/- 5.1, was correlated with sPVO, maximum diameter of right ventricle (RV), and right ventricle to left ventricle (RV/LV) ratio (r = .385, r = .415, and r = .329, respectively). The mean newly generated score was 10.9 +/- 5.5 and correlated with sPVO, maximum diameter of RV, and RV/LV ratio (r = .394, r = .483, and r = .393, respectively). Receiver operator characteristic (ROC) curve analyses revealed that sECG >= 3.5, s (ECG + SI) >= 4.5, and s (ECG + SI + ABG) >= 9.5 predict the severe PE patients with 70.6%, 61.8%, 58.8% sensitivities and 52.6%, 63.2%, 73.7% specificities, respectively. Conclusion: Adding the scores obtained from SI and ABG to the sECG enhances the specificity of sECG in predicting RVD (+) or severe PE patients, although a lesser degree decreasing in sensitivity may occur.