BACKGROUND: We compared thiopental sodium with propofol as induction agents under propofol-N2O anesthesia for cesarean sections. METHODS: We selected 68 pregnant women with a single fetus undergoing an elective cesarean section under general anesthesia and randomly allocated them to the thiopental sodium group (group N) or the propofol group (group P). Without premedication, thiopental sodium 5 mg/kg and succinylcholine 1 mg/kg were injected for induction in group N, and propofol 2 mg/kg and succinylcholine 1 mg/kg in group P. Propofol 10 mg/kg/hr was infused continuously with 50% N2O in both groups. We checked the blood pressure and the heart rate before and after injection. We analysed blood gas of maternal artery, umbilical artery, and umbilical vein at delivery and checked Apgar scores at 1 minute and 5 minutes after delivery. RESULTS: There was no significant difference in blood pressure, heart rate and Apgar scores between groups. Oxygen partial pressure (35.6 +/- 5.8 mmHg) and oxygen saturation (66.2 +/- 12.0%) of the umbilical vein in group P was higher than in group N (32.7 +/- 4.9 mmHg, 58.7 +/- 11.5%). Carbon dioxide partial pressure and pH did not differ between groups. CONCLUSIONS: There was no beneficial effect of thiopental sodium compared with propofol as an induction agent under propofol anesthesia. Propofol is a useful drug for cesarean sections.