All states provide Medicaid until the age of 19 years. After 19 years, young adults may become ineligible for Medicaid. Using the Medical Expenditure Panel Survey, we find that the resulting loss of Medicaid coverage causes substantial changes to the level and composition of health care use. The total number of visits to health care providers falls by over 60%, two-thirds of which is due to a decline in office visits. Expenditures, in particular inpatient expenditures, also appear to fall sharply. Copyright © 2014 John Wiley & Sons, Ltd.