Background: Black patients undergo coronary artery bypass grafting and percutaneous transluminal coronary angioplasty less often than white patients. It is unclear how racial differences in clinical factors contribute to this variation. Methods: A retrospective cohort study was performed of 666 male patients (326 blacks and 340 whites), admitted to 1 of 6 Veterans Affairs hospitals from October 1, 1989, to September 30, 1995, with acute myocardial infarction or unstable angina who underwent cardiac catheterization. The primary comparison was whether racial differences in percutaneous transluminal coronary angioplasty and coronary artery bypass grafting rates persisted after stratifying by clinical appropriateness of the procedure, measured by the appropriateness scale developed by the RAND Corporation, Santa Monica, Calif. Results: Whites more often than blacks underwent a revascularization procedure (47% vs 28%). There was substantial variation in black-white odds ratios within different appropriateness categories. Blacks were significantly less likely to undergo percutaneous transluminal coronary angioplasty (odds ratio, 0.30; 95% confidence interval, 0.14-0.63 [P<.01]) when the indication was rated 'equivocal.' Similarly, blacks were less likely to undergo coronary artery bypass grafting (odds ratio, 0.44; 95% confidence interval, 0.23-0.86 [P<.01]) when only coronary artery bypass grafting was indicated as 'appropriate and necessary.' Differences in comorbidity or use of cigarettes or alcohol did not explain these variations. Using administrative data from the Veterans Health Administration, we found no differences in 1-year (5.2% vs 7.4%) and 5-year (23.3% vs 26.2%) mortality for blacks vs whites. Conclusion: Among patients with acute myocardial infarction or unstable angina, variation in clinical factors using RAND appropriateness criteria for procedures explained some, but not all, racial differences in coronary revascularization use.