Total joint arthroplasties are recognized as being effective in the treatment of joint disease and making a significant difference in patients' quality of life. Understanding the trends and disparities in use of these procedures is important for policy decisions. However, research on these issues has been limited because of the suboptimal samples used. To study trends and racial and economic disparities associated with total hip and total knee arthroplasties, we used a large national database, Nationwide Inpatient Sample, 1996-2005, which may be best suited for elucidating trends and disparities in treatment use. Primary and revision hip and knee arthroplasties were the primary outcomes. Rates of use were computed by count per 100,000 persons in the population. Logistic regression was used to examine the associations between disparity factors and each outcome, where regressors included age, sex, race, regional income, hospital characteristics, payer, comorbidities, and obesity. Between 1996 and 2005, primary arthroplasty rates have increased, but revision rates only minimally. Racial disparities were larger than income disparities. Our study also revealed that racial disparities were not confined to the elderly or to low-income populations. This may mean that there is an unmet need for these medical procedures among racial minorities.