This study was conducted to report and compare bone mineral density (BMD) of the total body and distal forearm, as measured by X-ray absorptiometry, in 65 black and 73 white premenopausal women between the ages of 20 and 40. The black women had higher current and recalled body weights, a higher percent body fat, and more pregnancies and births, were younger at menarche, and reported lower alcohol intakes than the white women studied. A smaller percent of the black women had experienced amenorrhea, and a higher percent had lived at southern latitudes. Smoking history and lifetime use of oral contraceptives were similar in the two groups. Total body BMD, adjusted for body mass index (BMI), was 5.9% higher in the black than in the white women [mean +/- standard deviation (SD): 1.230 +/- 0.076 g/cm2 compared with 1.161 +/- 0.075; difference (95% confidence interval [CI95]: 0.068 (0.042, 0.095)]. Forearm BMD, adjusted for BMI, was 9.3% higher in the black women [mean +/- SD: 0.505 +/- 0.046 compared with 0.462 +/- 0.045; difference (CI95): 0.043 (0.027, 0.059)]. Adjustment for the other medical and lifestyle differences noted before had little effect on estimated BMD differences between the two groups.