The publications on recurrent abortion are abundant and confusing. Not surprisingly, the reason is insufficient knowledge about the physiology of normal pregnancy. It is an almost impossible task to investigate abnormality in pregnancy when the normal conditions are unknown. In addition, most of the reports on miscarriages are based on unsatisfactory scientific methods. We have carried out a critical review of the literature. We discuss the aetiology of the condition, and describe the practice in our department for investigating and treating women who experience recurrent abortion.