Introduction: The contraception has been practiced for over 4000 years and the prevalence of contraceptive use has increased worldwide.The Existing methods of contraception are not perfect and their acceptability is limited by side effects and inconvenience.Thus There is a real need for new methods of contraception to be developed. The effects of the follicular fluid on the pregnancy rate has been studied which can be intoduced as a possible method in interception or implantation control. Materials and Methods: 201, 3-7 month old, female Sprague Dawley and Albino NMRI rats were obtained from Razi Research Centre and were maintained under standard husbandry conditions with controlled temperature and 12 h light: 12 h dark photoperiod. Four females were caged overnight with males of the same age of proven fertility. Mating was evidenced by the appearance of vaginal plug on the following morning. Plugged females designated day 1 pregnant were caged separately and were devided randomly in three groups: 1) The experimental group which were injected filterated active follicular fluid transvaginally to the uterus on 5th days of pregnancy, 2) The placebo group that were injected Ham's F-10 on the same day, and 3) control group. The number of embryos per animal and percentage of pregnancy were evaluated. Results: The results indicate that statistically significant decrease in the pregnancy rate and the number of embryos per animal in the experimental (follicular fluid) group in comparison with the control and Ham's F-10 groups. Conclusion: As implantation is the result of an interaction between the receptive endometrium and the invasive blastocyst; follicular fluid which is an enzym-rich solution may act on either and leads to decrease of the pregnancy rate and number of embryos per rat. The exact mechanisms of these effects need elucidated studies. The results of this study show that the exposure of the endomertium/ or perimplantation embryo to the active follicular fluid might be considered as one of the interceptive methods.