Vaginal administration of prostaglandin analogues resulted in cervical changes that facilitated dilatation and evacuation in 80 patients in the late first trimester and the second trimester of pregnancy. When 0.5 mg and 1.0 mg of 15(S)-15-methyl-prostaglandin F2 alpha (15-ME-PGF2 alpha) was compared to 30 and 60 mg of 9-deoxo-16,16-dimethyl-9 methylene prostaglandin E2 (PGE2 analogue), the PGE2 analogue appeared to have more cervical ripening effect than did the 15-ME-PGF2 alpha. Overall, the 30 mg PGE2 vaginal suppository seemed to offer the most optimal combination of effectiveness, sufficient cervical dilatation, and minimal side effects. With the prostaglandins, maximal cervical effect was observed at 4 to 5 hours; this rapid effectiveness allows administration of the prostaglandin to accommodate a 1-day stay for surgical evacuation. The preoperative cervical priming results with the prostaglandins were compared to those obtained with the use of laminaria tents. Although the number of patients who needed further dilatation at the time of operation was less with the laminaria, the incidence of complications and the time for adequate dilatation were higher in that group.