This study was designed to examine the effect of the methanolic extract of the root of Cissampelos mucronata on embryo-foetal development in rats. A total of 60 nulliparous female rats weighing 143-215gm approximately 13 weeks of age in the proestrous stage were cohabited (1:1) with 60 male rats to obtain 40 pregnant rats which were assigned to four dosage groups (10 rats per group, I-IV) by random stratification to nearly equalized body weight difference between groups on gestataion day zero GD 0. Group I served as the control group while rats in Groups II, III and IV were administered with 100mgkg-1, 200mgkg-1and 300mgkg-1 doses of the extract respectively from implantation (GD6) to the day prior to the expected day of parturition (GD20). On GD20, the female rats were euthanized and uterine implantation data including live and dead foetuses were counted, weighed, gender determined and observed for external malformations. The results indicate that administration of the extract from gestation day 6 to 20 had no significant effect on the number of implantation sites while resorptions sites were significantly (p<0.05-0.001) high in a dose dependent manner. There was a decrease in the foetal weight, placental weight and crown rump length of the rats indicating that administration of the extract from gestation day 6 to 20 caused resorptions in pregnancy and decrease in foetal weight, placental weight and crown rump length rats in a dose dependent manner.Key words: Embryotoxic, crown rump, resorption, viable, foetu