The teratogenic effects of the ethanolic leaf extract of Momordicafoetida on the morphology of foetal Sprague Dawley rats was studied using 30 cyclic females and 5 males Sprague Dawley rats (weighing 200-300g) for the study. Vaginal lavage was taken daily to monitor their estrous cycle for 4 weeks. On the proestrous day of the cycle of each rat, a male rat was introduced into the cage, the presence of spermatozoa in the vaginal lavage was taken as day 1 of conception. The pregnant female Sprague Dawley rats were randomly divided into six groups which include group A1 and A2 (control), group B1 and B2 (anti-implantation) and group C1 and C2.Treated rats in group B1 and B2 received a double and single oral doses of 500mg/kg and 250mg/kg bw of the extract from post-coital day 1 to 10, while the control animals (A1) in this group received an equal volume of distilled water. All the animals were sacrificed on the day 12 of gestation to assess for anti-implantation effect. Treated rats in group C1 and group C2 received double and single oral doses of 500mg/kg and 250mg/kg bw of the extract from the 6th-19th day of gestation while the control animals (A1) in this group received an equal volume of distilled water. All the animals were sacrificed on the 12th day of gestation to assess for anti-implantation effect. All pregnant rats were sacrificed, fetuses were examined for malformation and gestational parameters monitored were: number of total implantation; resorption and dead fetuses. Live fetuses were weighed and examined for external malformations and variations. Fetal parameters recorded were: fetal numbers and weight, crown rump length, trans-umbilical cord length and placental weight. The results showed that there was prevention of implantation, abortion and significant reduction of parameters: crown rump-length, trans-umbilical cord length compared to the control (P<0.05). In conclusion, the above result suggest that the ethanolic extract of Momordicafoetida leaf at 500mg/kg body weight prevents implantation, induces abortion and significantly reduces fetal parameters in Sprague-dawley rats.