Death rates among US black men and women under 75 years of age are higher than for their white counterparts. The explanation for this excess risk, though attributed to socioeconomic factors, remains unclear. We calculated mortality rates by family income for blacks and whites in a representative sample of the US population (National Longitudinal Mortality Study). For persons aged less than 65 years of age, mortality rates are lower in those with higher family income for both blacks and whites, and both men and women. However, at each level of income, blacks have higher mortality than whites. Higher levels of family income are also associated with lower death rates from cardiovascular disease, cancer, and deaths from causes other than cardiovascular disease or cancer. After adjustment for income, blacks have higher death rates from each of these three general causes. For subjects below 65 years, the mortality gradient by income is larger than the gradient by race. The differences in mortality rates by race not accounted for by income may be due to other differences such as access to health care, type or quality of medical care, or behavioral risk factors that disadvantage black populations.