A study of patients with involution osteopathy has shown that the development of this disease is associated with osseous tissue dystrophic changes (osteoporosis) and, to a lesser extent, with osteomalacia. Involution osteopathy is not accompanied by severe changes in indices of phosphoric-calcium metabolism; it is characterized by a tendency to an increase in the levels of total and ionized calcium and a decrease in the level of serum phosphorus. A lowered level of calcitonin with a tendency to a decrease in the level of the somatotropic hormone and the unchanged content of parathormone was revealed in involution osteopathy. The blood level of sex steroids (both estradiol and testosterone) in women was decreased, a degree of a rise of gonadotropins in them was lower than that in healthy postmenopausal women. In men with involution osteopathy the mean level of serum testosterone was within low normal limits, the LH content remained normal, and a FSH level was raised. The level of prolactin in patients of both sexes was unchanged.