Objective: The purpose of this study was to determine which extracorporeal membrane oxygenation (ECMO) route best approximates the normal physiologic pattern of oxygenated blood distribution in fetal lambs submerged in warm saline solution. Study Design: Six fetal lambs ranging from 113 to 129 days of gestation were delivered by cesarean section and oxygenated with ECMO in a warm saline solution bath. We compared the distribution of oxygenated blood flow during intact placental circulation with 3 routes of ECMO, from the right atrium to the carotid artery (V-A), from the right atrium to umbilical vein (V-UV), and from the right atrium with umbilical artery to umbilical vein [(V + UA)-UV], in exteriorized fetal lambs. Distribution of oxygenated blood flow was determined by non-radioactive colored microspheres. Results: The ECMO blood flow rate through the catheters during V-A, V-UV or (V + UA)-UV ECMO ranged at 150 to 300 ml / min. Among the 3 different routes of ECMO, the oxygenated blood distribution in (V + UA)-UV showed the best correlation with placental-fetal blood flow, particularly in the brain and heart. Conclusion: This study indicated that (V + UA)-UV ECMO most closely approximates normal intact placental-fetal blood flow distribution in fetal lambs.