Abstract: Background and Objective: Biliary atresia (BA) is a congenital malformation characterised by a progressive fibrosing obliteration of the extra hepatic biliary system manifesting during the 1st week of life. The objective of this study was to investigate the teratogenic properties of aqueous extract of kola nitida as a cause of biliary atresia in wistar rats. Materials and Methods: Twenty adult female wistar rats were randomly distributed into 4 groups with weight ranging from 180-200 g. The female rats were grouped with 2 male rats for the purpose of mating. Following confirmation of pregnancy, variable oral doses of aqueous kola nut extract were given from 1 day of pregnancy till delivery of the pups. Data was analyzed by one-way analysis of variance (ANOVA) using SPSS. Results: The liver to body weight ratios of the pups were significantly reduced in treated groups compared to the control. Also, the average number of litters per rat was significantly reduced in treated groups compared to the control group. The liver enzymes, bilirubin (conjugated and total) and the histology of the livers were essentially normal. There was no other abnormality observed. No case of biliary atresia or other congenital abnormality was recorded following the administration of aqueous extract of kola nitida to the mother rat during pregnancy. Conclusion: The safety of the extract in pregnancy cannot be assured due to observation of reduced pup number and liver to body weight ratio in association with increased dosage.