Right ventricular (RV) functions are clinically important in acute pulmonary embolism (APE). Measurement of systolic function of the right ventricular outflow tract (RVOT) with echocardiography is a simple method to evaluate RV function. The aim of this study was to determine the relationship between RVOT systolic function and the Pulmonary Embolism Severity Index (PESI).A total of 151 patients diagnosed with APE by pulmonary computed tomography angiography or ventilation/perfusion scintigraphy were included. Patients were assigned to 2 groups based on the simplified PESI (sPESI): sPESI 1 patients (58.7±12.9 years vs. 61.1±12.7 years, respectively). Frequency of male gender was significantly higher in PESI <1 group (61.2% vs. 40.2%, p=0.013). No significant differences were found between the groups in fasting glucose, serum creatinine, hemoglobin, C-reactive protein, erythrocyte sedimentation rate, troponin, and D-dimer levels, and left ventricular ejection fraction. RVOT-FS was higher in patients with sPESI <1 than in patients with sPESI ≥1 (34.41±3.56 vs. 22.98±4.22), and this difference was significant (p<0.001). Tricuspid annular plane systolic excursion values were lower and pulmonary artery systolic pressure values were higher in the sPESI ≥1 group, which was also statistically significant (p<0.05). Mortality occurred in 7 patients with sPESI <1 and in 16 patients with sPESI ≥1. The mortality rate was higher in patients with lower RVOT-FS, and a RVOT-FS <0.22 predicted mortality with a sensitivity of 54.5% (AUC: 0.674, 95% CI 0.552-0.796; p=0.009).The RVOT-FS is a noninvasive measurement of RV systolic function, is well-correlated with the sPESI score, and associated with mortality in patients with APE. This easily applied measurement may be used to predict short-term mortality in patients with APE.