Studies based on a variety of primary data sets have consistently demonstrated that African Americans are about half as likely as whites to receive interventional therapy for coronary artery disease. Neither disease severity per se nor access to hospitals performing these procedures accounts for this finding. Likewise, available measures of income and ability to pay, including insurance status, do not explain the differences. Subtle personal factors, including physician bias and the willingness of patients to accept referral for surgery, may be important but have not as yet been measured. These findings present a challenge to the presumed equality in access to health care within the United States medical system. A new generation of health services research studies will be required to provide definitive reasons for this important disparity in treatment.