[Objective] To evaluate whether the combination of an antiprogestin (mifepristone) +aromatase inhibitors (letrozole or aminoglutethimide) or an iNOS inhibitor (aminoguandine) are effective in ending pregnancy during early gestation in rhesus monkeys. [Methods] The 30 pregnant monkeys were be randomly assigned five groups (treatment group:6 animals per group, but for 6 animals in control group) and to be undergone treatment with control group : Placebo (1ml/animal,), group A: Mifepristone (1mg/kg, sc.,), group B: Mifepristone(sc.) + Letrozole(2.5mg/animals, sc. ), group C: Mifepristone(1mg/kg,sc.) + aminoglutethimide(50mg/kg sc., bid,) and group D: Mifepristone(1mg/kg,sc.) + aminoguanidine(150mg/kg, sc., bid,) on d30, 31, and 32 of gestation. all the pregnant monkeys were be identified by ultrasound instrument on d29 of gestation. [Results] These results shown that 6/6 the animals in group B, C and D were effectively terminate the early pregnancy, the 3/6 animals in group A were be terminated pregnancy, and the 2/8 animals in control group were be terminated after treatment, and these combinations could also result in effective evacuation of the uterine cavity and reduce bleeding. [Conclusion] The paper suggested that the treatment will effectively terminate the early pregnancy in rhesus monkeys, the combination of agents used was likely to be more effective than the therapy in women and could reduce the long duration of bleeding associated with the present treatment, and might replace present therapy for medical abortion.