Although associated with adverse outcomes in other cardiovascular diseases, the prognostic value of an elevated white blood cell (WBC) count, a marker of inflammation and hypercoagulability, is uncertain in patients with pulmonary embolism (PE). We therefore sought to assess the prognostic impact of the WBC in a large, state-wide retrospective cohort of patients with PE. We evaluated 14,228 patient discharges with a primary diagnosis of PE from 186 hospitals in Pennsylvania. We used random-intercept logistic regression to assess the independent association between WBC count levels at the time of presentation and mortality and hospital readmission within 30 days, adjusting for patient and hospital characteristics. Patients with an admission WBC count <5.0, 5.0–7.8, 7.9–9.8, 9.9–12.6, and >12.6 × 109/L had a cumulative 30-day mortality of 10.9%, 6.2%, 5.4%, 8.3%, and 16.3% (P < 0.001), and a readmission rate of 17.6%, 11.9%, 10.9%, 11.5%, and 15.0%, respectively (P < 0.001). Compared with patients with a WBC count 7.9–9.8 × 109/L, adjusted odds of 30-day mortality were significantly greater for patients with a WBC count <5.0 × 109/L (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.14–2.03), 9.9–12.6 × 109/L (OR 1.55, 95% CI 1.26–1.91), or >12.6 × 109/L (OR 2.22, 95% CI 1.83–2.69), respectively. The adjusted odds of readmission were also significantly increased for patients with a WBC count <5.0 × 109/L (OR 1.34, 95% CI 1.07–1.68) or >12.6 × 109/L (OR 1.29, 95% CI 1.10–1.51). In patients presenting with PE, WBC count is an independent predictor of short-term mortality and hospital readmission. Am. J. Hematol. 88:677–681, 2013. © 2013 Wiley Periodicals, Inc.