The purpose of this report is to compare the distribution of total lipoprotein(a) [Lp(a)] mass in a population-based sample of blacks and whites, and to investigate the association of Lp(a) with other cardiovascular risk factors. A cross-sectional study design was used. Black and white men and women (n = 4125), aged 23-35 from the Coronary Artery Risk Development in Young Adults Study had the following data collected: Lp(a), lipids and lipoproteins, other metabolic parameters, anthropometry, physical activity, dietary intake, cigarette use, and alcohol use. Blacks had concentrations of Lp(a) approximately three-fold higher than whites. Medians were: black men 21.5 mg/dL, black women 23.9 mg/dL, white men 6.1 mg/dL, and white women 6.4 mg/dL. Lp(a) concentrations were higher in women than in men. Lp(a) was not consistently associated with smoking, alcohol consumption, physical activity, dietary fat, or obesity. In stepwise regression analyses in both blacks and whites, Lp(a) was consistently associated with low-density lipoprotein (LDL) cholesterol, fibrinogen, and apoB; regression models explained about 7% of the variance in Lp(a). In whites, Lp(a) tended to be higher in those with a positive family history of myocardial infarction. The large differences in Lp(a) between blacks and whites, and the absence of association with many other variables are consistent with previous suggestions that Lp(a) concentration is in large part genetically determined. The association of Lp(a) with LDL and fibrinogen, two strong risk factors for cardiovascular disease (CVD), could represent part of the mechanism of the CVD risk associated with Lp(a) in other studies. Longitudinal data are needed to determine the extent to which Lp(a) will independently predict disease, especially in diverse ethnic groups.