As the most common form of joint disease, osteoarthritis (OA) is associated with an extremely high economic burden. This burden is largely attributable to the effects of disability, comorbid disease, and the expense of treatment. Although typically associated with less severe effects on quality of life and per capita expenditures than rheumatoid arthritis, OA is nevertheless a more costly disease in economic terms because of its far higher prevalence. At the same time, the burden of OA is increasing. While direct and indirect per capita costs for OA have stabilized in recent years, the escalating prevalence of the disease-partly a function of the rapid increase in 2 major risk factors: aging and obesity-has led to much higher overall spending for OA. Approximately one-third of direct OA expenditures are allocated for medications, much of which goes toward pain-related agents. Hospitalization costs comprise nearly half of direct costs, although these expenditures are consumed by only 5% of OA patients who undergo knee or hip replacement surgery. However, while these surgeries are costly, they also appear to be quite cost-effective in the long term. Indirect costs for OA are also high, largely a result of work-related losses and home-care costs. Despite the need for wide-ranging and up-to-date data on the economics of OA treatment to clarify the most effective treatments and the best use of resources, this area of study has received insufficient research attention.