Background Post-traumatic pulmonary embolic events are associated with significant morbidity. Computed tomographic (CT) measurements can be predictive of right ventricular (RV) dysfunction after pulmonary embolus. However, it remains unclear whether these physiologic effects or clinical outcomes differ between early (<48 hours) vs late (≥48 hours) post-traumatic pulmonary embolism (PE). Methods All patients with traumatic injury and CT evidence of PE between 2008 and 2013 were identified. The study population was divided into 2 groups based on the time of diagnosis of the PE. The primary outcome was PE-related mortality. Results Fifty patients were identified (14 early PE and 36 late PE). Patients sustaining a late PE had a higher PE-related mortality rate (16.7% vs 0%), larger RV diameters, RV/left ventricular diameter ratios, RV volumes, and RV/left ventricular volume ratios (all P < .05). Conclusions Early post-traumatic PE appears to be associated with fewer RV physiologic changes than late post-traumatic PE and may be representative of primary pulmonary thrombosis. It remains to be seen whether early CT findings of PE should be managed according to previously established guidelines for embolic disease.