Habitual abortion should be defined as the spontaneous sequential loss of three or more pre-viable pregnancies. The incidence and etiology of spontaneous single and repeated, sequential abortion are discussed. The theoretical role of the various hormones in the treatment of abortion is examined. The modes of therapy now in effect are reviewed and their probable value estimated. Preconceptual therapy of the wife and husband for the successful salvage of a viable infant following previous sequential abortion is recommended. Logical postconceptual and emergency therapy is outlined for the patient who is an habitual aborter.A critical view of previous and present methods of study and treatment of habitual abortion is expressed.