Risk stratification of patients with acute pulmonary embolism (PE) assists with the selection of appropriate initial therapy and treatment setting. Patients with acute symptomatic PE that present with arterial hypotension or shock have a high risk of death, and treatment guidelines recommend strong consideration of reperfusion in this setting. For haemodynamically stable patients with PE, the combination of a negative clinical prognostic score and the absence of computed tomography-assessed right ventricle enlargement may accurately identify those at low-risk of short-term complications after the diagnosis of PE, and such patients might benefit from an abbreviated hospital stay or outpatient therapy. Some evidence suggests that the accumulation of factors indicating worse outcomes from PE on standard anticoagulation identifies the more severe stable patients with acute PE who might benefit from intensive monitoring and recanalization procedures, particularly if haemodynamic deterioration occurs. Current risk classifications have several shortcomings that might adversely affect clinical and healthcare decisions. Ongoing initiatives aim to address many of those shortcomings, and will hopefully help optimize risk stratification algorithms and treatment strategies.