Treatment of acute myocardial infarction differs between the United States and Canada, but the reasons for these practice pattern differences remain elusive. To investigate whether physician beliefs and access to procedures account for these differences in the treatment of acute myocardial infarction, a random sample of physicians involved in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial in the United States (n = 332) and Canada (n = 200) was surveyed. We found that American physicians recommend coronary angiography after uncomplicated infarction significantly more (median: 7 versus 3 of 11 possible indications, P = 0.0001). Coronary angiography, angioplasty, and bypass surgery were available in-hospital to more American than Canadian physicians (77% versus 41%), and the reported waiting period for cardiac procedures in a stable patient was longer in Canada (angiography: 28 versus 1.5 days; angioplasty: 30 versus 2 days; bypass surgery: 84 versus 3 days, all P < 0.001). More American than Canadian physicians were cardiologists (88% versus 74%), and more were interventional cardiologists (61% versus 26%). American physicians more highly rated the importance of patient requests, malpractice, and insurance coverage, whereas Canadians more highly rated availability of cardiac procedures as influencing clinical decisions. After statistical adjustment for these factors, however, Americans remained significantly more likely to recommend coronary angiography.