Background: Hemodynamic status and cardiac function are major pulmonary embolism (PE) prognostic factors. Although inflammation is considered a risk factor for deep vein thrombosis, the prognostic significance of the systemic inflammatory response syndrome (SIRS) and leukocytosis has not been well studied. Objective: This study evaluates PE prognostic factors, including SIRS and leukocytes. Patients/Methods: This retrospective cohort study included 667 PE patients. Risk evaluation included SIRS and leukocytosis. A prediction model was developed based on independent predictors of 30-day mortality. Results and Conclusions: Fifty-seven patients (8.5%) died within 30 days. Multivariate analysis showed that SIRS satisfying the WBC criteria (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.6-7.1), altered mental status (OR, 2.9; 95% CI, 1.2-7.4), and right-to-left ventricle diameter ratio (OR, 2.0; 95% CI, 1.1-3.7) were associated with 30-day mortality. SIRS criteria including body temperature (OR, 4.6; 95% CI, 1.4-14.8), heart rate (OR, 2.0; 95% CI, 1.1-3.6), respiratory rate (OR, 2.5; 95% CI, 1.4-4.6), and WBC count (OR, 1.9; 95% CI, 1.2-3.5) predicted short-term mortality in PE. The area under the receiver operating characteristic curve for the prognostic model`s prediction performance was 0.76 (95% CI, 0.66-0.85), and for pulmonary embolism severity index (PESI) and PESI + WBC count were 0.72 (95% CI, 0.68-0.75) and 0.76 (95% CI, 0.72-0.79, P＜0.01 versus PESI), respectively. Leukocytoes and SIRS are important factors in determining short-term outcomes.