Elevated red blood cell distribution width (RDW) has been associated with adverse outcomes of heart failure and pulmonary hypertension. A total of 702 consecutive patients with acute pulmonary embolism (PE) were evaluated. There was a graded increase in mortality rate with RDW quartiles of 5.8% in quartile I (<= 13.6), 9.7% in quartile II (13.7%-14.5%), 13.1% in quartile III (14.6%-16.3%), and 20% in quartile IV (> 16.3%; P < .001). Patients who died had higher baseline RDW values (16.1% [11.7-28.3] vs 14.5% [10.7-32.5]; P < .001). The optimal cutoff value of RDW for predicting in-hospital mortality was >= 15%. The area under the curve of mortality for RDW was 0.649 (confidence interval [CI]: 0.584-0.715); the negative predictive value was 93%. In multivariable regression analysis, RDW remained associated with an increased odds of death (odds ratio: 1.2, 95% CI: 1.1-1.4). High RDW level was an independent predictor of short-term mortality in PE. The RDW levels may provide a potential marker to predict outcome in patients with PE.