The effect of hormone replacement therapy on the bone mineral content of hypoestrogenic subjects depends on the pathogenesis of the disease as well as on the dosage and route of administration. This is particularly true in hypoestrogenism related to eating disorders. We present a longitudinal study of 26 young women with diet-induced amenorrhea compared with a group of subjects with POF. The study protocol included the quantification of weight loss, the endocrine profile (follicle-stimulating hormone, luteinizing hormone, prolactin, E2, FT3, FT4, thyroid-stimulating hormone, and cortisol), the evaluation of markers of bone turnover (GLA, OSTK-PR, ALP, OHP, and DPYR), and spinal bone density by DEXA at observation and after weight recovery. No hormone replacement therapy was administered. Mean BMD and Z scores before and after recovery do not differ significantly; OHP and DPYR appear significantly higher during basal evaluation, whereas GLA and ALP do not. Data on the impact of oral contraceptive use on bone mineral density are controversial. We particularly discuss the question of long-term treatment with 20 micrograms ethinyl estradiol pills on peak bone mass acquisition during adolescence.