The effectiveness of the antiandrogenic agent cyproterone acetate (CA) in its contraceptive form (2 mg CA + 50 micrograms ethinyl estradiol) in the treatment of osteoporosis associated with athletic amenorrhea was studied in seven high-performance athletes. Four women with similar characteristics served as controls. Their mean age was 21.9 years +/- 3.9. Training was started at a mean age of 14.0 years +/- 2.0. The mean training intensity expressed as kilometers run per week was 35 +/- 15. Mineral density was primarily affected by the hypoestrogenic status of these athletes (= 22 pg/ml +/- 8.8 in the midluteal phase). All participants showed low serum progesterone (= 2.85 ng/ml +/- 2.10) and LH profiles (= 5.6 mlU/ml +/- 0.8) during the midluteal phase. Cyproterone acetate was administered for 8 months to treat the increased bone loss in seven women athletes. Vertebral density appeared to be increased with 9.5% +/- 2.45% (mean +/- SD) while cortical base mineral content measured at the radius was not significantly changed. Our results demonstrate that cyproterone acetate administered in combination with estrogens provides a suitable therapeutic agent in the management of osteoporosis due to a hypoestrogenic status. This treatment could substitute other contraceptive agents. Moreover, women with the most severe estrogen deficiency showed a more pronounced reaction to this therapy.