The House Republican Budget Plan would make major changes to the structure of the Medicaid program. In this brief we estimate reductions in federal Medicaid spending due to both the repeal of the Affordable Care Act on Medicaid and the block grant provisions themselves. We find that the House Budget Plan would reduce federal spending by $1.4 billion between 2012 and 2021, a cut of 34 percent relative to current law. The impacts are greatest in states that would have the largest coverage expansions due to the Affordable Care Act. We also estimate the loss of Medicaid coverage that would be likely under different assumptions of states success in constraining spending. Finally we estimate the increase in state expenditures that would be necessary to maintain their current programs even assuming some cost containment success.