Pulmonary embolism is a common, often fatal condition that requires timely recognition and rapid institution of therapy. Previous studies have documented worse outcomes for weekend admissions for a variety of time-sensitive medical conditions. This phenomenon has not been clearly demonstrated for pulmonary embolism.We used the Healthcare Cost and Utilization Project Nationwide Inpatient Sample for the years 2000 to 2008 to identify people with a principal discharge diagnosis of pulmonary embolism. We classified admissions as weekend if they occurred between midnight Friday and midnight Sunday. We compared all-cause in-hospital mortality between weekend and weekday admissions and investigated the timing of inferior vena cava (IVC) filter placement and thrombolytic infusion as potential explanations for differences in mortality.Unadjusted mortality was higher for weekend admissions than weekday admissions (OR, 1.19; 95% CI, 1.13-1.24). This increase in mortality remained statistically significant after controlling for potential confounding variables (OR, 1.17; 95% CI, 1.11-1.22). Among patients who received an IVC filter, a larger proportion of those admitted on a weekday than on the weekend received it on their first hospital day (38% vs 29%, P < .001). The timing of thrombolytic therapy did not differ between weekday and weekend admissions.Weekend admissions for pulmonary embolism were associated with higher mortality than weekday admissions. Our finding that IVC filter placement occurred later in the hospital course for patients admitted on weekends with pulmonary embolism suggests differences in the timeliness of diagnosis and treatment between weekday and weekend admissions. Regardless of cause, physicians should be aware that weekend admissions for pulmonary embolism have a 20% increased risk of death and warrant closer attention than provided during the week.