Objective: Deep vein thrombosis (DVT) and pulmonary embolism (PE), collectively known as venous thromboembolism (VTE), are well-known complications of total knee or hip arthroplasty (TKA and THA). This study examined the economic burden of VTE in arthroplasty surgeries from a US hospital perspective. Methods: Patients at least 18 years old undergoing TKA and THA from January 1, 2002 to December 30, 2006 were extracted from a large, nationwide inpatient database. Rates of events, length of hospital stay, inpatient costs and reimbursed amounts (available for a small subset that could be linked to managed care data) were evaluated. Multivariate analyses were conducted on hospital costs to adjust for differences in demographic and clinical characteristics. Results: Out of 259,524 hip and knee surgeries (mean age of 67 years), 1.0% of patients diagnosed with VTE during hospitalization (0.6% DVT only and 0.4% PE [with or without DVT]). Compared to patients without VTE, mean length of stay (LOS) for those with VTE was twice as long (8 vs. 4, p<0.0001) and hospital costs were 48.0% higher ($20,850 vs. $14,092, p<0.0001). Within the limited subset that had linked managed care claims data (n=5002), mean cost of patients with VTE was 23.5% higher ($16,877 vs. $13,662, p<0.0023); however, the amount reimbursed was on average 6.4% higher ($14,121 vs. $13,272, p=0.77). After multivariate adjustment, DVT increased costs by $1421 following TKA and $3,950 following THA; PE increased costs by $2862 following TKA and $4355 following THA (p<0.0001 for all). Conclusion: Experiencing VTE complications substantially adds to the costs of TKA or THA. The increased hospital costs of patients with VTE did not appear to be adequately reimbursed. The overall economic impact of implementing prophylaxis to prevent VTE events can be projected.