The development of safe, effective, nonsurgical methods of pregnancy termination has the potential to avert significant maternal mortality and morbidity, especially in developing countries. RU-486 blocks the action of progesterone and cortisol, leading to structural changes in the endothelium of decidual capillaries, decidual necrosis, and subsequent detachment of the products of conception. When RU-486 is administered in conjunction with a low dose of a prostaglandin such as misoprostol, the abortion rate is comparable to that for vacuum aspiration (e.g., 94-96%). This regimen is contraindicated, however, in women aged 35 years and older, smokers, and those with medical problems such as diabetes, hypertension, clotting disorders, or anemia. In countries with strict abortion laws, RU-486 has been used to induce menstrual bleeding in women whose periods are delayed up to 10 days. An obstacle to more widespread acceptance of RU-486 has been its medicalization through national guidelines that stipulate waiting periods or require multiple visits to an approved abortion clinic. Women are likely to prefer RU-486 over surgical abortion because it allows the patient more control over her pregnancy termination and is less invasive. As political controversy continues to delay RU-486's introduction to the US and most developing countries, there are concerns that the drug will become a black market commodity used for self-induction.