One hundred and twenty term women (> 37.5 weeks amenorrhea) with unripe cervixes (Bishop < 4) and with a clear clinical indication for labour induction were randomized to receive either mifepristone (RU 486) or placebo. The patients' regimens consisted of 200 mg of mifepristone on days 1 and 2 over an observation period of 4 days, with labour induction planned for day 4. Within 12 hours after taking the first tablet, fetal distress was diagnosed in 8 patients (3 in the Mifepristone group and 5 in the control group), who underwent immediate cesarean section. These 8 patients could not therefore participate in our survey and have been excluded from the final results. Forty one patients had spontaneous onset of labour, 31 in the mifepristone group and 10 in the control group (p < 0.001). Forty seven patients needed cervical maturation with prostaglandin, 32 from the control group and 13 from the mifepristone group (p < 0.001). Thirteen patients in each group had cervical maturation sufficient for classical labour induction. We noted that patients delivering vaginally needed significantly lower amount of oxytocin in the mefepristone group and that the mean time interval between day 1 and the onset of labour was also significantly shorter in this group. The high cesarean section rate (32%), which is equivalent in both the placebo and the treated groups, may be attributed to the fact most of the patients in this survey had high risk pregnancies. There was no difference in the occurrence of fetal distress during labour in the 2 groups. Neonatal parameters were similar in both groups. These results establish mifepristone as an induction agent for the initiation of labour in term women. Though more studies are needed, Mifepristone has shown itself to be safe and appropriate in situations where labor has to be induced in term women.