One-quarter of practicing physicians in the United States are graduates of international medical schools. The quality of care provided by doctors educated abroad has been the subject of ongoing concern. Our analysis of 244,153 hospitalizations in Pennsylvania found that patients of doctors who graduated from international medical schools and were not U.S. citizens at the time they entered medical school had significantly lower mortality rates than patients cared for by doctors who graduated from U.S. medical schools or who were U.S. citizens and received their degrees abroad. The patient population consisted of those with congestive heart failure or acute myocardial infarction. We found no significant mortality difference when comparing all international medical graduates with all U.S. medical school graduates.