This analysis of Commonwealth Fund survey data estimates the economic impact of health problems on worker productivity. In 2003, an estimated 18 million adults ages 19 to 64 were not working and had a disability or chronic disease, or were not working because of health reasons. Sixty-nine million workers reported missing days due to illness, for a total of 407 million days of lost time at work. Fifty-five million workers reported a time when they were unable to concentrate at work because of their own illness or that of a family member, accounting for another 478 million days. Together, labor time lost due to health reasons represents lost economic output totaling $260 billion per year. Workers without paid time off to see a physician are more likely to report missing work or being unable to concentrate at their job.