OBJECTIVE. Describe our experience with the RU 486 (mifepristone) in case of pregnancy termination induced by sulprostone. METHOD. Prospective non controlled study in the department of Fetal Medicine of the "Institut de Puericulture de Paris". 158 women undergoing termination of pregnancy during the second and third trimester received a single dose of 600 mg of RU 486, 36 hours prior to infusion of 100 micrograms/hour of sulprostone. MAIN OUTCOME MEASURES. Delay between sulprostone therapy and diagnosis of labour duration of delivery. Prostaglandin doses used and frequency of secondary effects. RESULTS. The mean time between sulprostone administration and diagnosis of labour (146.5 +/- 106 minutes) as well delay of delivery (592.2 +/- 504 minutes) corresponded to the results reported in the literature. The primigravid women needed higher doses of prostaglandin and consequently experienced more secondary effects. No severe secondary effects were observed in this study. CONCLUSION. RU 486 is a satisfactory treatment for pregnancy termination during the second or third trimester.