We performed a pilot study to examine the clinical efficacy of mifepristone 200 mg followed on the same day by misoprostol 800 microg vaginally in women with pregnancies up to 49 days gestation. Forty women received mifepristone 200 mg after which they self-inserted misoprostol intravaginally 6 to 8 h later at home. Participants returned for an evaluation, including transvaginal ultrasonography, 24 +/- 1 h after using the misoprostol. Participants who had not aborted received a second dose of misoprostol to administer 48 h after the mifepristone. All participants returned approximately 2 weeks after receiving mifepristone. At 24 h after receiving misoprostol, 37/40 (92%, 95% CI 81-98%) had ultrasonographic evidence of complete abortion. By follow-up 2 weeks after the mifepristone, 40/40 (100%, 95% CI 92-100%) women were felt to have complete abortions. One subject subsequently had a suction aspiration for an incomplete abortion on study Day 44. Nausea, vomiting, diarrhea, and warmth/chills occurred in 38%, 13%, 13%, and 60%, respectively. This pilot study suggests that mifepristone 200 mg, followed on the same day by misoprostol 800 microg vaginally, effects abortion at rates comparable to regimens using the standard time interval of 48 h between medications.