OBJECTIVE: To compare misoprostol 25 micrograms administered at 2-hour intervals with intracervical prostaglandin (PG) E2 in women with Bishop scores of 5 or less. METHODS: Subjects were randomly assigned to receive either misoprostol 25 micrograms every 2 hours or a commercially available intracervical preparation containing 0.5 mg of PGE2 gel administered at 6-hour intervals for a maximum of two doses. RESULTS: Women who received misoprostol experienced a significantly reduced mean time (+/- standard deviation) from drug administration to onset of three contractions in 10 minutes, 6.7 +/- 5.8 versus 12.4 +/- 9.6 hours (P = .007). Mean time to rupture of membranes was also shorter in the misoprostol group, 9.7 +/- 5.5 versus 13.6 +/- 6.8 hours (P = .01), as was the mean time to delivery, 16.0 +/- 7.7 versus 22.4 +/- 10.9 hours (P = .006). Three patients in the misoprostol group experienced uterine hypertonus but not related fetal morbidity. CONCLUSION: Misoprostol is more effective than intracervical PGE2 in bringing about labor and delivery, but further work is needed to determine the ideal dosing regimen.