Objective: To compare the effectiveness of Misoprostol administered intravaginally every 12 versus 6 hours for termination of pregnancy in the first and second trimesters. Methods: Fifty six pregnant patients at 7 – 22 weeks of gestation were randomized to receive 800 μg (first trimester) and 200 μg either every 12 or every 6 hours for 48 hours. Results: The incidence of abortion within 48 hours after initial dose, in the first trimester was 100% in the two groups, in the second trimester the incidences were 95.5 and 100%. The incidences of abortion by a single dose in the first trimester were 85 and 10% in the 12 and 6 hours groups respectively (P <0.001) The mean abortion intervals 8.3 , 20.2 and 12.4 hours in the 12 and 6 hour group respectively. Side effects were similar in both groups. Conclusion: Misoprostol administered vaginally is effective for termination of first and second trimester pregnancies in non scared uterus. Giving the medication at a shorter interval from 12 to 6 hours appeared to have no significant benefit.