Immune thrombocytopenic purpura (ITP) is associated with low platelet counts and, consequently, a high risk of adverse events leading to hospitalization. However, there are few data on the clinical and economic burden of hospitalizations for ITP. The Nationwide Inpatient Sample (NIS) database of discharges, a stratified 20% sample of all United States (US) community hospitals across all payers, was used to evaluate discharges in ITP patients. We developed nationally representative numbers of discharges in ITP patients from 2003 to 2006 based on diagnosis codes. Using appropriate weights for each NIS discharge, we created national estimates of average cost, length of stay, and in-hospital mortality for specific groups of ITP-related hospitalizations. Approximately 129,000 discharges occurred between 2003 and 2006 in ITP patients. The average cost associated with all discharges in 2008 dollars was 16,476, with a 6.4-day length of stay and in-hospital mortality of 3.8%. In contrast, the average cost of all hospitalizations in the US population during the same period was 10,039, the average length of stay was 4.8 days, and in-hospital mortality was 2.5%. Mortality risk was higher for ITP patients than for the standard US population adjusted for age and gender, with a relative mortality ratio of 1.5 (95% CI: 1.4–1.6). On the basis of a nationally representative sample of US discharge records from 2003 to 2006, hospitalization with ITP represents an economically and clinically important event. ITP was associated with higher costs, longer stays, and more in-hospital deaths on average than all other hospitalized patients combined. Am. J. Hematol. 2009. © 2009 Wiley-Liss, Inc.