The abortifacient efficacy and complication rate of the administration of hypertonic saline intraamniotically to 796 women were compared with those following administration of various prostaglandins by several routes to 3783 women. Intraamniotic administration of 2.5 mg 15-methyl-PGF2α or repeated vaginal administration of 15-methyl PGF2α methyl ester were both highly effective. The interval from treatment to abortion following prostaglandin administration was significantly shorter than that following hypertonic saline. The frequency of complications varied with prostaglandin compound and route of administration but was generally of the same magnitude as that following hypertonic saline administration. None of the prostaglandin-treated patients experienced epileptic seizures, and no maternal deaths occurred.