Utilization rates of aspirin, beta blockers, angiotensin-converting enzyme inhibitors, and statins singly and as part of a multidrug regimen before hospitalization were measured in 109,540 patients with a history of coronary artery disease presenting with acute myocardial infarction to 1,283 hospitals participating in the National Registry of Myocardial Infarction-4. The profile of patients receiving none or only 1 of these therapies was compared with that of patients receiving any 3 or all 4 agents. Most patients (58%) with a history of coronary artery disease presenting with acute myocardial infarction were on none or only 1 of these effective medications at hospital admission. Only 21% of patients were on >or=3 of these therapies. Older age, female gender, and Medicare or no insurance coverage was significantly associated with previous receipt of <or=1 agent. Patients from New England or with a history of diabetes mellitus, hypertension, or hyperlipidemia were more likely to have received >or=3 of these therapies. In conclusion, data from this large national registry have indicated that most patients with a history of CAD were not receiving the recommended combination of cardiac medications before their AMI.