OBJECTIVE: To evaluate the safety, efficacy, and acceptability of an oral drug regimen of medical abortion compared with surgical abortion. MATERIALS AND METHODS: 500 women with amenorrhea < 56 days chose either surgical abortion or 600 mg of mifepristone (RU-486) followed by 400 microg of misoprostol after 48 h. RESULTS: Medical regimen had more side effects than surgical abortion, including bleeding, cramping, nausea and vomiting. Only fever was more frequent in the surgical method. The failure rates for medical abortion exceeded those for surgical abortion, 16.0% vs. 4.0%. The adolescents' failure rate in the medical regimen group was only 1.7%. Several failures on medical abortion were not true drug failures, but surgical interventions not medically necessary (misdiagnosis). Women were satisfied with either method, but more preferred medical abortion. CONCLUSION: Medical methods are safe, effective, simpler and potentially allow greater privacy than surgical abortion methods. Therefore, medical methods could be the method of choice for abortion, particularly for adolescents.