['Many persons with depressive disorder are not treated and associated costs are not recorded.', 'To determine whether major depressive disorder (MDD) is associated with higher medical cost among Medicare recipients.', 'Four waves of the Baltimore-Epidemiologic Catchment Area (Baltimore ECA) Study conducted between 1981 and 2004 were linked to Medicare claims data for the years 1999 to 2004 from the Centers for Medicare and Medicaid Services (CMS). Generalized linear models specified with a gamma distribution and log link function were used to examine direct medical care costs associated with MDD.', 'Medicare recipients with no history of MDD in either the ECA or CMS data had mean six-year medical costs of US $40,670, compared to $87,445 for Medicare recipients with MDD as recorded in CMS data and $43,583 for those with MDD as recorded in Baltimore-ECA data. Multivariable regressions found that compared to Medicare recipients with no history of depression, those with depression identified in the CMS data had significantly higher medical costs; about 1.87 times (95% confidence interval (CI) 1.32 to 2.67) higher. Medicare recipients with a history of depression identified in the ECA data were no more likely to have higher costs than were Medicare recipients with no history of depression (relative ratio 1.33, 95% CI 0.87 to 2.02).'] Does cOSTS OF DEPRESSION FROM claim DATA FOR MEDICARE RECIPIENTS IN A POPULATION-BASED SAMPLE?