To examine the impact of amenorrhea on bone mineral density in women of reproductive age, we performed a cross sectional study in 190 amenorrheic women, comprising 113 premature ovarian failure, 27 primary hypothalamic amenorrhea, 38 hyperprolactinemia and 12 Sheehan's syndrome. Measurement of bone mineral density was carried out using dual photon absorptiometry at four sites: femur neck, ward's triangle, trochanter and spine (L2-4) and we compared the result with that of 163 normal-cycle control women with age matched. Bone mineral densities was significantly low in patients with primary hypothalamic amenorrhea and premature ovarian failure at all four sites. In those with hyperprolactinemia a decrease in bone mineral density was noted at femur neck and spine while those with Sheehan's syndrome is associated with decreased bone density at femur neck, ward's triangle and trochanter. The degree of bone loss and the affected sites seems differ depending on the type of amenorrhea. In patients with primary hypothalamic amenorrhea, significant bone loss was already noted at all four sites by age 20. The decrement in bone density continued rapidly during the early twenties up to age 25 and then slowed after age 25. In those with premature ovarian failure with secondary amenorrhea there were no decrease in bone mineral density within the first year after onset of amenorrhea, however, in the subsequent 2 years, the reduction in BMD was rapid and thereafter the reduction slowed remarkably. The BMD in this study positively correlated with the body mass index and negatively with the phosphorus intake.