Background: Labor induction is becoming one of the most frequent procedures in maternity hospitals. However, the optimal agent for labor induction has not yet been established. Misoprostol, a prostaglandin E1 analogue, is receiving much attention due to its labor induction properties. Objective: The aim of this study was to evaluate the efficacy and safety of 25 and 50 mcg of intravaginal misoprostol, every four hours, for the induction of labor. Materials and Methods: This was a randomized controlled study to compare two different regimens of vaginal misoprostol, in women with obstetrical or medical indication for induction of labor. Participants received either a 25- or 50-mcg dose of misoprostol inserted into the posterior vaginal fornix repeated every four hours (maximum six doses), until adequate labor was established. Close monitoring of uterine activity and fetal heart rate was performed in all patients. Data were collected prospectively on epidemiological, obstetric, and care aspects. Results: Both regimens of misoprostol were effective in the induction of labor and most of the women had normal vaginal deliveries (81.08%). Although the mean time intervals from induction to the onset of active labor, and from induction to vaginal delivery for the 50-mcg regimen were lower, there was no significant difference between the two regimens. There were very few complications, with one case of uterine tachysystole in each treatment regimen. Conclusion: The results of the present study show that both regimens of misoprostol appear to be effective for the induction of labor in patients with indication, with few fetal complications.