Older adults with mild cognitive impairment (MCI) should receive evidence-based treatments when indicated. Providers and patients may overestimate the risk of dementia in patients with MCI leading to potential under-treatment. However, the association between pre-existing MCI and receipt of evidence-based treatments is uncertain. To compare receipt of treatments for acute myocardial infarction (AMI) between older adults with pre-existing MCI and cognitively normal patients. Prospective study using data from the nationally representative Health and Retirement Study, Medicare, and American Hospital Association. Six hundred nine adults aged 65 or older hospitalized for AMI between 2000 and 2011 and followed through 2012 with pre-existing MCI (defined as modified Telephone Interview for Cognitive Status score of 7-11) and normal cognition (score of 12-27). Receipt of cardiac catheterization and coronary revascularization within 30 days and cardiac rehabilitation within 1 year of AMI hospitalization. Among the survivors of AMI, 19.2% had pre-existing MCI (55.6% were women and 44.4% were male, with a mean [SD] age of 82.3 [7.5] years), and 80.8% had normal cognition (45.7% were women and 54.3% were male, with a mean age of 77.1 [7.1] years). Survivors of AMI with pre-existing MCI were significantly less likely than those with normal cognition to receive cardiac catheterization (50% vs 77%; P < 0.001), coronary revascularization (29% vs 63%; P < 0.001), and cardiac rehabilitation (9% vs 22%; P = 0.001) after AMI. After adjusting for patient and hospital factors, pre-existing MCI remained associated with lower use of cardiac catheterization (adjusted hazard ratio (aHR), 0.65; 95% CI, 0.48-0.89; P = 0.007) and coronary revascularization (aHR, 0.55; 95% CI, 0.37-0.81; P = .003), but not cardiac rehabilitation (aHR, 1.01; 95% CI, 0.49-2.07; P = 0.98). Pre-existing MCI is associated with lower use of cardiac catheterization and coronary revascularization but not cardiac rehabilitation after AMI.