Seventy-six consecutive patients undergoing midtrimester abortion were randomly divided into treatment with either intracervical and (less so) extraamniotic prostaglandin E2 (PGE2) gel or intraamniotic prostaglandin F2.alpha. (PGF2.alpha.). At the end of 5 h the initial treatment was supplemented by an oxytocin drop and in the PGE2 group the intracervical application of gel was repeated if necessary. The second day a third application of PGE2 gel was administered to a few women. The two groups were comparable with regard to age, parity and gestational age. There was no statistical difference between the two groups in success rate during the 48 h study period (93% for PGE2 versus 97% for PGF2.alpha.) or in the average induction-to-abortion interval (16.8 h for PGE2 versus 16.6 h for PGF2.alpha.). The frequency of completed abortions was statistically significantly higher and the gastrointestinal side-effects significantly lower in the PGE2-treated patients as compared to the PGF2.alpha.-treated subjects. Further, there were fewer complications and the pethidine consumption in women treated with intracervical PGE2 was lower as compared to patients treated with intraamniotic PGF2.alpha.. In conclusion, an intracervical PGE2 gel is found applicable and more advantageous than intraamniotic PGF2.alpha. in midtrimester abortion. It is safe, convenient and equally easy to administer during the early and the later parts of the second trimester.