Spontaneous abortion, or the early termination of pregnancy without outside interference, may be caused by fetal, maternal or external factors. In many cases, a specific etiology may never be identified. A variety of clinical presentations are possible, ranging from imperceptible loss to profound life-threatening shock. Physicians should be able to diagnose and manage the six recognized types of spontaneous abortion: threatened, inevitable, incomplete, complete, missed and septic. In all cases, uterine evacuation, avoidance of complications and psychologic support of the family are important. The prognosis for a subsequent successful pregnancy is good, except in cases of habitual abortion.