Misoprostol and mifepristone have been shown to be effective for medical abortion up to 9 weeks of gestation. When used alone, the successful complete abortion rate dropped to approximately 60%. It has been demonstrated that by adding water to misoprostol, the success rate rose to 92%. This is the first randomized study to investigate the efficacy of misoprostol and water versus misoprostol alone for first trimester medical abortion in women at </= 9 weeks of gestation. Eighty women were randomly assigned to group 1 (water added to misoprostol) and group 2 (misoprostol alone). Vaginal misoprostol 800 microgram was given on days 1, 3 and 5. If the woman did not require vacuum aspiration during the period up to the return of first menstruation after medical abortion, the outcome was classified as complete abortion. The incidence of side-effects and the acceptability were assessed through a standardized questionnaire during and after the abortion. The complete abortion rate appeared higher when water was added but the difference did not reach statistical significance. Gastro-intestinal side-effects were common but well tolerated in both groups. Overall, 40% of the women preferred a surgical method in the future because of the high failure rate. With an overall complete abortion rate of 85%, it is probably not a clinically acceptable method even if the addition of water can improve the results. We conclude that the addition of water onto misoprostol tablets does not improve its efficacy in first trimester medical abortion. Misoprostol alone is not recommended for medical abortion (up to 9 weeks of pregnancy) because of the high failure rate and low acceptability.