Technological advances during the past decade have yielded new knowledge of luteal function and its regulation. A number of new substances with luteotrophic and lutcolytic properties have been identified in the corpus luteum, and the picture which emerges of the mechanisms responsible for physiological luteolysis is becoming increasingly complex. As luteal function/regulation during the menstrual cycle in the absence of pregnancy differs both from that in normal pregnancy, and from that in pathological pregnancy, these advances in our knowledge should prove clinically useful, particularly with regard to the early diagnosis and management of pathological pregnancy.