There are limited data available concerning the influence of obesity, a major cardiovascular disease risk factor, in relationship to coronary artery disease (CAD). This is of considerable importance to African-Americans since African-Americans have one of the world's highest CAD mortality rates coupled with the fact that obesity is extremely prevalent in this population. The present study assessed the relationship between body mass index and CAD in African-Americans undergoing coronary angiography. Eight hundred sixty-six available cardiac catheterization reports between the years 1983 through 1990 were retrospectively reviewed at Howard University Hospital in Washington, D.C. CAD was prevalent in 59.6% and 41.2%, males and females, respectively. Among the males overweight and obesity were found in 22.4% and 20.9%, respectively, compared to 39.6% and 30.6% for females. An upside-down U-shaped relationship between BMI and CAD was found. The interpretation of this finding is that being overweight is associated with increased risk of CAD compared to the lean and obese.