Few studies have evaluated between-country differences in medical care and survival after acute myocardial infarction, and none have compared the US with countries from Eastern Europe. Comparable data from the US (Atherosclerosis Risk in Communities Study [US-ARIC]) and Poland (Multinational Monitoring of Trends and Determinants in Cardiovascular Disease project [Pol-MONICA]) were developed. From 1987 through 1993, a total of 3,694 patients were hospitalized with acute myocardial infarction events in the 2 Pol-MONICA communities and 4,801 in the 4 US-ARIC communities. Patients in the US-ARIC were 1.7 times more likely to be treated in a coronary care unit and received cardiac procedures, calcium channel blockers, and thrombolytic agents significantly more often than patients in the Pol-MONICA. The use of antiplatelet agents, nitrates, angiotensin-converting enzyme inhibitors, and beta blockade agents was similar in both countries. Case fatality (28-day) rates after hospitalized acute myocardial infarction were nearly identical (men, 7% in Pol-MONICA vs 6% in US-ARIC; women, 9% in Pol-MONICA vs 8% in US-ARIC). However, when fatal coronary heart disease events not associated with a hospitalized myocardial infarction were included, the US-ARIC rates were less than half than those seen in Pol-MONICA. Substantial differences in treatment of hospitalized acute myocardial infarction between countries did not translate into a survival advantage for patients reaching clinical attention. Differences in case severity, arising from the high out-of-hospital coronary death rate in Poland may play an important role in this finding.