Uterine blood flow, maternal hemodynamics, and fetal and maternal blood gases were measured before, during and after the administration of methoxamine and ephedrine to pregnant monkeys during normotension under nitrous oxide-oxygen analgesia. Methoxamine increased maternal blood pressure and total peripheral vascular resistance and decreased cardiac output, maternal heart rate, and uterine blood flow. Ephedrine increased maternal heart rate, but did not alter blood pressure, total peripheral vascular resistance, cardiac output, or uterine blood flow. While the fetus was unaffected by ephedrine, it manifested signs of asphyxia with methoxamine. After the vasopressors were discontinued uterine blood flow decreased with ephedrine and increased with methoxamine.