The purposes of this study were to compare the lumbar spine bone mineral density of eumenorrheic and amenorrheic white subjects aged 15 to 21 years, and to describe the femoral neck bone mineral density in the eumenorrheic subjects. Twenty-eight eumenorrheic females had lumbar bone mineral density (mean +/- SD) of 1.213 +/- 0.117 g/cm2, and femoral neck bone mineral density of 1.032 +/- 0.092 g/cm2 measured with dual energy x-ray absorptiometry. Bone mineral density at neither site was related to age, energy intake, or calcium intake. Femoral neck bone mineral density was related to energy expenditure. Body composition was measured with total body electrical conductivity, and bone mineral density at both sites was related to body weight as much as fat-free mass. Eight amenorrheic subjects had a lumbar spine bone mineral density of 1.057 +/- 0.113 g/cm2, which was lower than in the eumenorrheic group. However, when controlling for weight, this difference was not significant. Peak lumbar and femoral neck bone mineral density may be reached at midadolescence.