In order to compare the pharmacokinetic properties of propofol in pregnant and nonpregnant females, the authors undertook to study 10 women with singleton pregnancies scheduled for elective cesarean section and 6 nonpregnant females undergoing elective laparoscopic tubal sterilization. All patients were free of significant systemic diseases or complications of pregnancy. General anesthesia for cesarean section patients was carried out with all generally recognized precautions. Anesthesia for both groups was induced with a propofol dose of 2.0 mg/kg injected over 20 seconds, neuromuscular blockade was maintained with atracurium after intubation, and anesthesia was produced with nitrous oxide-enflurane. Venous blood samples were obtained before induction and then periodically for 480 minutes after propofol injection. Samples were chromatographically analyzed for propofol concentrations and the data employed to derive pharmacokinetic parameters: distribution and elimination half-lives, apparent central volume of distribution, apparent volume of distribution at steady state, and clearance.