Anxiety disorders are estimated to affect 26.9 million individuals in the United States at some point during their lives. This study used the human capital approach to estimate the direct and indirect costs of these highly prevalent disorders. In 1990, costs associated with anxiety disorders were $46.6 billion, 31.5% of total expenditures for mental illness. Less than one-quarter of costs associated with anxiety disorders were for direct medical treatment; over three-quarters were attributable to lost or reduced productivity. Most of these indirect costs were associated with morbidity, as mortality accounted for just 2.7% of the total. Greater availability of effective, relatively low-cost outpatient treatment could substantially reduce the economic and social burden of these common and often crippling disorders.