Under the Affordable Care Act (ACA), states can extend Medicaid eligibility to more low-income adults, but little is known about the health care needs and health risks of these individuals. In this study, Kenney, Long and colleagues, Sandra Decker and Deliana Kostova from the National Center for Health Statistics, use data from the National Health and Nutrition Examination Survey and find that compared with adults currently enrolled in Medicaid, uninsured low-income adults potentially eligible to enroll in Medicaid under the ACA have a lower prevalence of many chronic conditions but that the uninsured adults with these chronic conditions are less likely to be aware that they have them and less likely to have the condition under control. The rates of undiagnosed and uncontrolled chronic health problems indicate that millions of low-income uninsured adults are currently at risk of premature mortality and other significant health issues. These findings provide new evidence of the potential health benefits associated with the Medicaid expansion under the ACA.