The effects of the α-adrenergic agonists, norepinephrine and methoxamine, and the α-antagonist, phenoxybenzamine, on umbilical and uterine blood flows, fetal and maternal heart rates, arterial and venous pressures were examined in near-term chronic sheep preparations. Norepinephrine injection or methoxamine infusion to either fetus or ewe resulted in a respective unilateral fetal or maternal pressor response associated with bradycardia. Uterine blood flow decreased significantly with α-agonist administration to either fetus or ewe. Umbilical blood flow did not change with either, but an increase in calculated umbilical vascular resistance did occur after fetal administrations of the α-agonist. Thus, both the uterine and umbilical vascular beds are responsive to α-agonism, but maternal uteroplacental perfusion appears to be more sensitive. α-Blockade in either fetus or mother produced no significant changes in umbilical or uterine blood flows or fetal or maternal perfusion pressure suggesting that basal α-adrenergic tone is unnecessary for normal maintenance of either fetal or maternal uteroplacental circulation.