Abstract: Objective To study the teratogenicity of Euratorium adenophorum spreng extract in rats.Methods According to toxicological test methods of pesticides for registration,the pregnant rats were divided into 5 groups:three Euratorium adenophorum spreng extract dosage groups(1000,500,200 mg/kg),negative control group and positive control group(300 mg/kg aspirin).Euratorium adenophorum spreng extract and aspirin were given orally from 6th to 16th day of gestation.The pregnant rats were sacrificed on the 20th day of gestation.Embryonic and fetal developmental parameters were surveyed.The appearance,viscera and skeleton of the fetuses were examined.Results Absorbed fetus rate in moderate and high dose groups was 7.62% and 15.08%,show ing obvious increases compared with negative control group.There was no difference in the rate of fetal mortality and weight gain in all treated and negative control group.The weight,body length and tail length showed no significant difference between the treated groups and negative control group.Euratorium adenophorum spreng extract didn't induce obvious teratogenic effect on the appearance,viscera and skeleton of the fetuses.Conclusion Euratorium adenophorum spreng extract exert a certain embryotoxicity,but has no apparent teratogenicity in rats.