Cessation of ovarian activity is accompanied by a more or less marked and more or less accelerated reduction in bone mass; the degree and speed of the process--which occurs in all women--depends on individual (genetic factors influencing peak bone mass, duration of child-bearing period), iatrogenic (treatment with corticosteroids or thyroid hormones) or accidental factors (post-traumatic immobilization). Whatever the factor that triggers off the process, the end result is the destruction of bone tissue. This process may be documented by hematochemical (Nordin's test) and instrumental parameters (MOC and similar techniques). Oestroprogestin (and to a lesser extent calcitonin) hormone replacement therapy has been demonstrated to be highly efficacious in countering this involutive process. The authors report data obtained following the evaluation of 35 women in menopause undergoing. Nordin's test and measurement of the plasma level of estradiol using RIA, before and after twelve months after the start of osteoprotective treatment. Of the 35 patients 9 received only progestin, 22 an oestroprogestin combination (of these 18 patients received estrogen transdermally and 4 orally), and 4 calcitonin administered parenterally. A statistically significant positive correlation with Nordin's test was only found in the group receiving oestrogen therapy. In conclusion, it may be affirmed that in the absence of contraindications oestrogens represent the elective form of treatment for menopausal osteoporosis. Acceptable results have been reported in the literature also using calcitonin, but this treatment could not be evaluated in this study owing to the reduced number of the sample treated.