Objective: To compare the safety and efficacy of misoprostol and oxytocin for induction of labor. Methods: One hundred thirty women requiring induction of labor were randomized to receive either intravenous oxytocin or 100 mu g misoprostol, administered intravaginally every 4 hours until labor was established. Results: Compared with women receiving oxytocin, a greater percentage of women in the misoprostol group had Bishop scores of 3 or less (58 versus 38%, P < .05). Nonetheless, the median induction-to-delivery interval was significantly shorter (585 versus 885 minutes, P < .001) in the misoprostol group. Women in the misoprostol group were more likely to deliver vaginally within 24 hours of the start of induction (77 versus 55%, P < .002). Epidural analgesia was used more frequently in women receiving oxytocin than in those receiving misoprostol (73 versus 50%, P = .025). The total percentage of cesarean deliveries was not significantly different, although the percentage of cesarean deliveries for dystocia was lower in the misoprostol group (8 versus 21%, P = .02). Uterine tachysystole was significantly more common (70 versus 11%, P < .001) and hospital charges significantly less with misoprostol. Conclusion: Compared with oxytocin for labor induction, misoprostol results in a shorter induction-to-delivery interval, a reduction in the rate of cesarean delivery for dystocia, and a decreased use of epidural analgesia. Uterine tachysystole is significantly more common with the use of misoprostol. Copyright (C) 1997 by The American College of Obstetricians and Gynecologists.