Abstract: ObjectiveTrichlorfon,an organophosphate pesticide,was evaluated for its potential effects to produce terato-genicity,reproductive and endocrine toxicity following maternal exposure during organogenesis in mice.MethodsThe pregnant mice were randomly divided into 4 groups,3 for exposed and 1 for control,and were administrated doses of 0,12.5,25 and 50mg/kg trichlorfon respectively by gavage on gestation day 6 through day 15.All the mice were sacrificed on gestation day 17,in the mean time,the repr oductive,endocrine and develo pmental to xicity were evaluated.Results(1)The rate of malformed fetuses were obviously incr eased in each exposed group compared with that of control group,(P<0.01).(2)Exposure to trichlorfon during or ganog enesis,show ed no obvious effects on mater nal reproduction and gestation,such as maternal weights gain,ovary viscer a coefficient、placenta viscera coefficient,number of corporalutea,number of implantation sites, number of live fetuses,number of dead fetuses and number of resorbed fetuses(P>0.05).(3)There was no obviously affection in the concentr ation of serum and ovary estradiol in all groups except the concentration of serum estradiol was significantly reduced in 50mg/kg group(P<0.05).ConclusionUnder the doses of this study,it is suggested that trichlorfon causes teratogenicity without significant maternal reproductive and endocrine toxicities after maternal exposure during organogenesis.