The natural estrogens have proved their value in the treatment of the severe menopausal syndrome, vaginitis of children and senile women, and certain types of amenorrhea, migraine and abnormal breast hyperplasia. Two principal drawbacks attend the clinical use of the natural estrogens—the high cost, especially when large doses are required, and the loss of potency when administered orally. The advantage of the oral administration of endocrine products in the attempt to overcome a relative or actual deficiency is apparent when one recollects that the various hormones are normally produced in minute quantities at a relatively steady rate. This process cannot be imitated by hypodermic injections at intervals of two or three days. For these and other less important reasons, the need of an orally potent, synthetic estrogen is constantly engaging the attention of the biochemist and the clinician. When Dodds and his associates1announced in 1938 the synthesis of