Pulmonary venous admixture (𝑄̇xs/𝑄̇xt) was determined in nine nonpregnant sheep and in seven pregnant sheep during their last trimesters of gestation. Pulmonary venous admixture was greater in the pregnant animals (5.7 ± 1.6% of the cardiac output; mean ± SD) than in the nonpregnant ones (4.2 ± 1.3% p < 0.05). On consecutive days, four local anesthetics were infused in random order via a femoral venous catheter into each sheep for 30 minutes. Total doses of 1.8 mg/kg of bupivacaine, 2.7 mg/kg of etidocaine, 6 mg/kg of lidocaine, and 15 mg/kg of chloroprocaine were administered. None of the anesthetics induced a significant change in pulmonary venous admixture.