AIM: To evaluate the alterations of maternal hepatic drug-metabolizing enzymes and antioxidative function in tobacco-induced intrauterine growth retardation (IUGR). METHODS:Pregnant rats were assigned to control group and tobacco group. IUGR model was produced by smoking from gestational days (GD) 9 to GD 20. Fetuses were removed by laparotomy on GD 21. The fetal development parameters such as fetal body weights, litter size and placental weights were recorded. Subcelluar fractions of liver were prepared by differential centrifugation. Activities of drug-metabolizing and antioxidative enzymes were monitored. RESULTS:In the tobacco exposure group, fetal body weights, litter size and placental weights were significantly reduced (P