In a woman of fifty-eight years, many of whose bones had almost disappeared as a result of Paget's disease, together with a severe postmenopausal osteoporosis, massive estrogen therapy was followed almost at once by a remission of clinical symptoms and by actual reconstitution of bone. Withdrawal of the estrogen produced an exacerbation; its readministration was again followed by improvement. For over two years the patient has been kept on daily doses of from 2,000 to 10,000 rat units (0.33 to 1.66 milligrams) of estradiol benzoate; during this time she has maintained her improvement and has showed no untoward symptoms.