The effect of calcium and oestrogen therapy on theexcretion of total hydroxyproline, calcium and phosphorus in 23 asymptomatic postmenopausal women has been evaluated. A temporary significant reduction in total hydroxyproline and phosphorus excretion in the group with calcium therapy has been observed. No effect in the oestrogen-treated group has been observed. Therapy with calcium supplements seems to be of value. An interrupted calcium therapy, however, is to be preferred to a continuous therapy.