BACKGROUND Invasive and noninvasive cardiovascular imaging is beneficial in the care of patients admitted with acute myocardial infarction. Little is known about patients' cumulative radiation exposure. RESULTS All patients admitted with an acute myocardial infarction to any of 49 University HealthSystem Consortium member hospitals from 2006 to 2009 were reviewed for inpatient procedures involving ionizing radiation that included chest radiograph, computed tomogram scans, radionuclide imaging, diagnostic cardiac catheterization, and percutaneous coronary intervention. The average cumulative effective radiation dose per patient was estimated on the basis of published typical effective radiation doses for imaging procedures. Patients (n=64 071) admitted for acute myocardial infarction had a median age of 64.9 years. A total of 276 651 procedures involving ionizing radiation were performed during the study period, a median of 4.3 procedures per patient per admission. The majority of patients had invasive catheterization (77%), followed by computed tomogram scans (52%), mostly body examinations. The median cumulative effective radiation dose delivered was 15.02 mSv per patient per acute myocardial infarction admission. Postprocedural bleeding was a significant predictor of radiation exposure (odds ratio, 2.01; 95% confidence interval, 1.85 to 2.18), together with postprocedural mechanical complications resulting from device implantation (odds ratio, 2.86; 95% confidence interval, 2.61 to 3.13). Patients with higher underlying clinical complexity (defined by severity of illness scores) had higher radiation exposure and higher mortality (P<0.0001). There was also significant geographic variation in radiation exposure; patients in New England received the lowest cumulative exposure (odds ratio, 0.78; 95% confidence interval, 0.74 to 0.81). CONCLUSIONS Acute myocardial infarction inpatients are exposed to an approximate median radiation dose of 15 mSv. This exposure is a result of multiple cardiovascular and noncardiovascular procedures. Efforts should be made to understand the risks and benefits of radiation exposure per episode of care for acute myocardial infarction.