Few epidemiologic studies have investigated the impact of body mass index, low educational attainment, cigarette smoking, and physical activity on the considerable black-white difference in waist-to-hip ratio. These relationships were assessed with multivariable linear regression among 3,094 adults (24% black) who were examined in 1987 in South Carolina. The unadjusted mean waist-to-hip ratio was lower for black men than for white men (-0.03 units) and higher for black women than for white women (+0.03 units). After adjustment for age, body mass index, education, smoking, and physical activity, the black-white difference in mean waist-to-hip ratio was -0.02 units (p < 0.001) among men and +0.01 units (p < 0.01) among women. Although differing distributions of age, body mass index, and educational attainment accounted for a 59% reduction in the black-white difference among women, these factors did not explain the difference among men. Thus, these results suggest that other environmental or biologic factors may also play an important role in the marked variation in body fat distribution between the two ethnic groups. The results also support the importance of the prevention of cigarette smoking and overweight in potentially preventing abdominal obesity in both black adults and white adults.