Hemodynamic status and cardiac function are important factors for predicting pulmonary embolism (PE) prognosis. Although inflammation is considered a risk factor for deep vein thrombosis, the prognostic significance of both systemic inflammatory response syndrome (SIRS) and leukocytosis has not been elucidated. This study evaluates PE prognostic factors, including SIRS and leukocytes. 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. Fifty-seven patients (8.5%) died within 30 days of PE. Multivariate analysis showed that SIRS satisfying the WBC criteria (odds ratio OR, 2.8; 95% confidence interval CI, 1.5-5.4), altered mental status (OR, 4.0; 95% CI, 1.8-8.7), shock (OR, 2.6; 95% CI, 1.0-7.1), and right-to-left ventricle diameter ratio (OR, 1.7; 95% CI, 1.0-2.8) 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 white blood cells (WBC) count (OR, 1.9; 95% CI, 1.2-3.5) predicted short-term mortality following PE. The area under the receiver operating characteristic curve for the prognostic model performance was 0.76 (95% CI, 0.66-0.85); 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 < 0.001 versus PESI), respectively. Leukocytosis and SIRS are important factors in determining short-term outcomes in PE patients.