Rapid and accurate risk stratification is critical in determining the optimal treatment strategy for patients with acute pulmonary embolism (PE). Early identification of patients with normal blood pressure and a favorable prognosis (low-risk PE) might select a subset of patients for outpatient treatment, which is associated with reduced cost and improved patient satisfaction, and has been shown to be effective and safe. Alternatively, identification of normotensive patients deemed as having a high risk for PE-related adverse clinical events (intermediate-high-risk PE) might select a subset of patients for close observation and consideration of escalation of therapy. Clinical prognostic scores have been gaining importance in the classification of patients into these categories. They should be derived and validated following strict methodological standards, and their use in clinical practice should be encouraged.