The effects of caffeine consumption on rates of change in bone mineral density (BMD) were examined in 205 healthy, nonsmoking, postmenopausal women. BMD of the spine and total body were measured by dual-energy x-ray absorptiometry, and dietary intakes by food-frequency questionnaire. Among women with calcium intakes above the median (744 mg/d), 1-y rates of bone change--adjusted for years since menopause, body mass index, physical activity, and baseline BMD--did not differ by caffeine intake. However, among women consuming less calcium, those with the highest caffeine intakes (> 450 mg/d) had significantly more bone loss (ANCOVA, P < 0.05) than did women consuming less caffeine (0-171 and 182-419 mg/d). Percent change in BMD by lowest to highest tertile of caffeine consumption was 0.26 +/- 2.74, 0.70 +/- 2.70, and -1.36 +/- 2.70 at the spine and -0.19 +/- 1.24, 0.23 +/- 1.23, and -0.68 +/- 1.25 at the total body. Daily consumption of caffeine in amounts equal to or greater than that obtained from about two to three servings of brewed coffee may accelerate bone loss from the spine and total body in women with calcium intakes below the recommended dietary allowance of 800 mg.